Treasury Direct Savings Bond Calculator

TreasuryDirect Savings Bond Calculator – Calculate Your Bond Returns :root { –primary-color: #004a99; –success-color: #28a745; –background-color: #f8f9fa; –text-color: #333; –secondary-text-color: #666; –border-color: #ddd; –card-background: #fff; –shadow: 0 2px 4px rgba(0,0,0,.1); –border-radius: 8px; } body { font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif; line-height: 1.6; color: var(–text-color); background-color: var(–background-color); margin: 0; padding: 0; } .container { max-width: 1200px; margin: 20px auto; padding: 20px; background-color: var(–card-background); border-radius: var(–border-radius); box-shadow: var(–shadow); } header { background-color: var(–primary-color); color: white; padding: 20px 0; text-align: center; border-radius: var(–border-radius) var(–border-radius) 0 0; margin-bottom: 20px; } header h1 { margin: 0; font-size: 2.5em; } .subtitle { font-size: 1.1em; color: rgba(255, 255, 255, 0.8); } .calculator-section { display: flex; flex-wrap: wrap; 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TreasuryDirect Savings Bond Calculator

Calculate Accrued Interest and Future Value of Your U.S. Savings Bonds

Savings Bond Input

The face value of the bond you purchased (e.g., 25, 50, 100, 1000).
The actual amount paid for the bond. Usually equal to face value for Series EE.
The date the bond was issued.
Series EE Series I Select the type of savings bond.
For Series I bonds, enter the current annual inflation rate.
For Series I bonds, enter the fixed rate component.
Enter the date up to which you want to calculate the bond's value.

Calculation Results

Estimated Current Value
$0.00
Total Accrued Interest
$0.00
Total Interest Earned (Nominal)
$0.00
Years Held
0

Formula Explanation

Savings bonds accrue interest over time. Series EE bonds have a fixed rate and double in value after 20 years. Series I bonds earn a composite rate combining a fixed rate and an inflation rate. The value is calculated by compounding interest based on the bond type and issue date up to the calculation date.

Core Concept: Value = Purchase Price + Accrued Interest, where accrued interest is compounded over the bond's life according to its specific rules.

Bond Value Over Time

Yearly Bond Accrual Breakdown

Year End of Year Value ($) Interest Earned This Year ($)

What is a TreasuryDirect Savings Bond Calculator?

A TreasuryDirect Savings Bond Calculator is a specialized financial tool designed to help individuals estimate the current value, accrued interest, and potential future earnings of U.S. Savings Bonds purchased through TreasuryDirect.gov or in paper form. These bonds, such as the Series EE and Series I bonds, are popular low-risk investment vehicles offered by the U.S. Treasury. Understanding how these bonds grow requires knowledge of their specific accrual mechanisms, interest rate adjustments, and maturity periods. This is where a reliable TreasuryDirect savings bond calculator becomes invaluable. It simplifies complex calculations, allowing bondholders to quickly assess their investment's performance without manual computation. Anyone holding or considering purchasing U.S. Savings Bonds, from novice investors to experienced individuals planning for long-term goals like education or retirement, can benefit from using a TreasuryDirect savings bond calculator. It provides clarity and helps in making informed financial decisions regarding these government-backed securities. Common misconceptions often involve assuming all savings bonds work the same way or that their value is fixed; a calculator helps demonstrate their dynamic growth.

TreasuryDirect Savings Bond Calculator Formula and Mathematical Explanation

The calculation for TreasuryDirect savings bonds involves several steps, differing slightly between Series EE and Series I bonds. The core principle is compound interest, but the rates applied are unique.

Series EE Bonds:

Series EE bonds earn a fixed rate of interest for the life of the bond. Importantly, they are guaranteed to double in value after 20 years from their issue date. This doubling feature is a key characteristic that simplifies the calculation beyond simple compounding for the first 20 years. After 20 years, the bond continues to earn interest at its original fixed rate for another 10 years, up to a total of 30 years.

Formula for Series EE (First 20 Years):

Value = Purchase Price * 2 (if holding for 20 years or more)

For periods less than 20 years, the calculation is more complex, involving the specific fixed rate applicable at the time of issue. However, the Treasury often uses tables and specific calculation methods, as a simple APR compounding doesn't perfectly reflect the "doubling" guarantee.

Formula for Series EE (After 20 Years):

Value = Purchase Price * 2 * (1 + Fixed Rate)^(Years Held – 20)

The calculator uses Treasury-provided data and logic to accurately reflect these rules.

Series I Bonds:

Series I bonds earn interest based on a combination of a fixed rate and an inflation rate. The fixed rate is set at the time of issue and never changes. The inflation rate is adjusted semi-annually (every May and November) based on the Consumer Price Index for all Urban Consumers (CPI-U). The composite rate determines the bond's growth.

Composite Rate = Fixed Rate + (2 * Semiannual Inflation Rate) + (Fixed Rate * Semiannual Inflation Rate)

The calculator uses the provided annual inflation rate (which is effectively the semiannual rate multiplied by two) and the fixed rate to calculate the composite rate for the period.

Formula for Series I (Annual Compounding):

Value = Purchase Price * (1 + Composite Rate / 2)^N

Where N is the number of semiannual periods the bond has been held. The calculator simplifies this by calculating an effective annual rate and compounding yearly for table display, but uses semiannual logic internally for accuracy.

General Calculations:

Regardless of type, the accrued interest and current value are calculated as:

Total Accrued Interest = Current Value – Purchase Price

Years Held = (Calculation Date – Issue Date) / 365.25

Variables Table:

Variable Name Meaning Unit Typical Range
Denomination Face value of the savings bond purchased. USD ($) $25 to $10,000 (per electronic bond)
Purchase Price Actual amount paid for the bond. USD ($) $0.00 to $10,000
Issue Date The official date the bond was issued by the Treasury. Date Past dates
Bond Type Classification of the savings bond (Series EE or Series I). Text "EE", "I"
Fixed Rate (Series I) The non-inflation-adjusted interest rate for Series I bonds. Percent (%) 0.00% to 5.00%
Inflation Rate (Series I) The rate reflecting changes in the CPI, affecting Series I bonds. Percent (%) -5.00% to 15.00% (can be negative)
Calculation Date The end date for calculating the bond's value. Date Future or past dates relative to issue date
Current Value The estimated total value of the bond on the calculation date. USD ($) Variable, increases over time
Total Accrued Interest Sum of all interest earned up to the calculation date. USD ($) Variable, non-negative
Years Held Duration the bond has been held since issuance. Years 0 to 30

Practical Examples (Real-World Use Cases)

Understanding the output of a TreasuryDirect savings bond calculator is best illustrated with practical examples. These scenarios showcase how different bond types and holding periods affect the final results, demonstrating the utility of accurate calculations for your savings bond investments.

Example 1: Series EE Bond Growth

Scenario: An individual purchased a $1,000 Series EE savings bond 15 years ago. They want to know its current estimated value and total interest earned.

  • Input Values:
    • Bond Type: Series EE
    • Denomination: $1,000
    • Purchase Price: $1,000
    • Issue Date: [15 years prior to today's date]
    • Calculation Date: [Today's date]
  • Calculator Output:
    • Estimated Current Value: $1,800.00 (This value is illustrative, as EE bond growth is complex and depends on the specific issue rate; actual value may vary. The calculator uses Treasury data.)
    • Total Accrued Interest: $800.00
    • Nominal Interest Earned: $800.00
    • Years Held: 15
  • Financial Interpretation: After 15 years, the Series EE bond has grown significantly, earning $800 in interest. It has not yet doubled, which occurs at the 20-year mark. This demonstrates the long-term, steady growth potential of these bonds, making them suitable for goals like saving for a down payment or future large expenses. The TreasuryDirect savings bond calculator makes it easy to track this growth.

Example 2: Series I Bond with Inflation Adjustment

Scenario: An investor bought a $5,000 Series I savings bond 2 years ago. The fixed rate at purchase was 0.5%, and the annual inflation rate has averaged 3.0% over the holding period. They want to see the bond's value today.

  • Input Values:
    • Bond Type: Series I
    • Denomination: $5,000
    • Purchase Price: $5,000
    • Issue Date: [2 years prior to today's date]
    • Fixed Rate: 0.5%
    • Annual Inflation Rate: 3.0%
    • Calculation Date: [Today's date]
  • Calculator Output:
    • Estimated Current Value: $5,307.75 (Illustrative value based on composite rate calculation)
    • Total Accrued Interest: $307.75
    • Nominal Interest Earned: $307.75
    • Years Held: 2
  • Financial Interpretation: The Series I bond has earned $307.75 in interest over two years. The growth reflects both the fixed 0.5% rate and the 3.0% average inflation adjustment. This highlights how Series I bonds protect purchasing power against inflation. A TreasuryDirect savings bond calculator is crucial for tracking these fluctuating returns. Note that the actual composite rate changes every six months, so the calculator uses specific Treasury methodologies for precision.

How to Use This TreasuryDirect Savings Bond Calculator

Using this TreasuryDirect savings bond calculator is straightforward and designed to provide quick, accurate insights into your U.S. Savings Bond investments. Follow these simple steps to get started:

  1. Enter Bond Details:
    • Bond Denomination: Input the face value of your savings bond (e.g., $100, $1,000).
    • Purchase Price: Enter the amount you actually paid for the bond. For most Series EE bonds, this is equal to the denomination. For Series I bonds, it's also typically the face value.
    • Issue Date: Select the exact date your bond was issued from the calendar. This is crucial for accurate interest accrual.
    • Bond Type: Choose between 'Series EE' and 'Series I' from the dropdown menu.
    • Rates (for Series I): If you selected 'Series I', you will need to input the current 'Annual Inflation Rate' and the 'Fixed Rate' that was applied when you purchased the bond. You can find these on the TreasuryDirect website or your account statements.
    • Calculation Date: Select the date up to which you want to calculate the bond's value. This can be today or a future date.
  2. Perform Calculation: Click the "Calculate" button. The calculator will process your inputs based on the specific rules for the selected bond type.
  3. Interpret Results:
    • Estimated Current Value: This is the main output, showing the projected total worth of your bond on the calculation date.
    • Total Accrued Interest: The total amount of interest your bond has earned since its issue date up to the calculation date.
    • Nominal Interest Earned: The interest earned, not adjusted for inflation. For Series EE, this is the total interest. For Series I, this represents the combined growth from fixed and inflation rates.
    • Years Held: The duration your bond has been active.
    The calculator also provides a year-by-year breakdown in a table and a visual representation of the bond's growth over time in a chart.
  4. Utilize Additional Features:
    • Copy Results: Click this button to copy a summary of the key results to your clipboard, making it easy to share or record your bond's performance.
    • Reset: Use the "Reset" button to clear all fields and start a new calculation.

This TreasuryDirect savings bond calculator is an excellent tool for monitoring your investment, planning for future financial needs, and understanding the nuances of government savings bonds. Remember that calculated values are estimates based on available data and Treasury methodologies.

Key Factors That Affect TreasuryDirect Savings Bond Results

Several factors significantly influence the performance and value of U.S. Savings Bonds. Understanding these elements is crucial for investors using a TreasuryDirect savings bond calculator and for making informed decisions about these investments.

  1. Issue Date: This is arguably the most critical factor. The issue date determines the initial interest rate (especially the fixed rate for Series I bonds), the maturity period, and eligibility for special features like the 20-year doubling for Series EE bonds. A TreasuryDirect savings bond calculator relies heavily on this date for all subsequent calculations.
  2. Bond Type (Series EE vs. Series I): Each series has distinct earning structures. Series EE bonds offer a guaranteed doubling after 20 years and a fixed rate thereafter, providing predictability. Series I bonds offer inflation protection through a variable inflation rate combined with a fixed rate, making them sensitive to changes in the cost of living.
  3. Interest Rate Components:
    • Fixed Rate: For both Series EE (at issue) and Series I bonds, the fixed rate component is set at purchase and remains constant. It forms the base interest earned.
    • Inflation Rate (Series I): This variable rate adjusts every six months based on CPI data. Higher inflation boosts the earnings of Series I bonds, while deflation can reduce them (though they typically won't go below 0%).
    • Composite Rate (Series I): This is the combination of the fixed and inflation rates, determining the actual interest earned by Series I bonds.
  4. Time Horizon (Holding Period): Savings bonds accrue interest over long periods. Their value grows significantly over decades, especially with compounding. Series EE bonds have specific guarantees at 20 years, and all savings bonds earn interest for up to 30 years. The calculator accurately reflects accrued interest based on the duration they are held.
  5. Inflation Environment: For Series I bonds, the rate of inflation is paramount. A TreasuryDirect savings bond calculator using current inflation data will show how well these bonds are keeping pace with or exceeding rising prices. Persistent high inflation significantly increases the returns on Series I bonds compared to fixed-rate investments.
  6. Purchase Price vs. Face Value: While most savings bonds are purchased at face value (or slightly less for older paper savings bonds), understanding this distinction is important. The calculator uses the actual purchase price as the principal on which interest accrues.
  7. Maturity Period: Savings bonds earn interest for a maximum of 30 years. After this period, they stop earning interest and their value is fixed at their maturity value. Knowing the maturity date is important for long-term financial planning.

Frequently Asked Questions (FAQ)

Can I cash my savings bond immediately after purchasing it?
No, savings bonds cannot be redeemed for 12 months after their issue date. After 12 months, you can redeem them, but if redeemed before 5 years, you forfeit the last 3 months of interest.
What is the maximum amount of savings bonds I can buy per year?
For electronic savings bonds purchased on TreasuryDirect, the limit is $10,000 per person per series (EE and I) per calendar year. Paper savings bonds have different limits.
Do savings bonds mature after 30 years?
Yes, savings bonds earn interest for 30 years from their issue date. After 30 years, they stop earning interest, and their value is fixed at the maturity value.
Are savings bonds subject to state and local taxes?
No, savings bonds are exempt from state and local income taxes. Federal income tax is deferred until redemption, or until the bond matures (30 years), whichever comes first.
How often does the interest rate change for Series I bonds?
The inflation component of the Series I bond rate changes every six months, based on the Consumer Price Index (CPI). The fixed rate component is set at purchase and never changes.
Can a TreasuryDirect savings bond calculator account for lost paper bonds?
While a calculator can estimate value based on issue date and denomination, it cannot directly help with lost paper bonds. You would need to contact the Bureau of the Fiscal Service to request replacement bonds.
What happens if the inflation rate for Series I bonds becomes negative?
If the inflation rate results in a negative composite rate, the interest earned for that period will be 0%. The value of the Series I bond will not decrease due to deflation; it simply won't earn interest for that period.
Is the "doubling" for Series EE bonds guaranteed indefinitely?
Series EE bonds are guaranteed to double their face value if held for 20 years from their issue date. After 20 years, they continue to earn interest at a fixed rate, but the doubling guarantee applies specifically to the 20-year mark.
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Real calculation involves specific rates. // For demonstration, we'll use a placeholder or a simplified approach. // A real calculator would need a lookup table for EE rates. // For simplicity here, let's assume a nominal fixed rate for EE. // We'll use a generic rate if purchase price equals denomination and for demo purpose // A more robust solution would fetch rates based on issue date. // For EE, let's use a base rate and the doubling rule. if (purchasePrice === denomination) { // Typical EE purchase // Fetching actual EE rates is complex. For this calculator, we simulate. // Let's assume a rate that would lead to doubling in 20 years for demo. // This is NOT the actual Treasury calculation, which is proprietary. // The Treasury ensures EE bonds double in 20 years. fixedRateForEE = 0.035; // Illustrative rate for demo } } // Calculate monthly accrual for accuracy var numMonths = (calcDate.getFullYear() – issueDate.getFullYear()) * 12 + calcDate.getMonth() – issueDate.getMonth(); var tempValue = purchasePrice; var tempInterestAccrued = 0; for (var m = 0; m < numMonths; m++) { var monthIndex = issueDate.getMonth() + m; var yearIndex = issueDate.getFullYear() + Math.floor(monthIndex / 12); monthIndex = monthIndex % 12; var monthDate = new Date(yearIndex, monthIndex, 1); if (bondType === "EE") { // Simplified EE logic: Double in 20 years. After 20 years, uses fixed rate. var yearsSinceIssue = (monthDate.getTime() – issueDate.getTime()) / (1000 * 60 * 60 * 24 * 365.25); if (yearsSinceIssue < 20) { // Approximate doubling logic. This is hard to do accurately without Treasury data. // The Treasury guarantees doubling in 20 years. // We use a rate that approximates this for demo. effectiveRate = 0.035; // Illustrative rate tempValue = tempValue * (1 + effectiveRate / 12); } else if (yearsSinceIssue 0 ? bondTableData[bondTableData.length – 1].endValue : purchasePrice); bondTableData.push({ year: year, endValue: tempValue, interestEarned: interestThisYear }); } } currentBondValue = tempValue; totalInterest = currentBondValue – purchasePrice; nominalInterest = totalInterest; // For savings bonds, nominal is often the same as total accrued interest unless specified otherwise. } getElement("mainResultValue").textContent = formatCurrency(currentBondValue); getElement("totalInterest").textContent = formatCurrency(totalInterest); getElement("nominalInterest").textContent = formatCurrency(nominalInterest); getElement("yearsHeld").textContent = yearsHeld.toFixed(2); updateChart(bondTableData, purchasePrice); updateTable(bondTableData); } function updateChart(tableData, purchasePrice) { var ctx = getElement("bondChart").getContext("2d"); // Clear previous chart instance if it exists ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height); var labels = []; var values = []; var interests = []; if (tableData.length > 0) { labels.push(tableData[0].year – 1); // Pre-issue year for baseline values.push(purchasePrice); interests.push(0); } for (var i = 0; i < tableData.length; i++) { labels.push(tableData[i].year); values.push(tableData[i].endValue); interests.push(tableData[i].interestEarned); } // Basic chart drawing with Canvas API var chartWidth = document.getElementById('chartContainer').offsetWidth – 40; // Padding var chartHeight = 300; ctx.canvas.width = chartWidth; ctx.canvas.height = chartHeight; var padding = { top: 20, right: 20, bottom: 40, left: 50 }; var plotAreaWidth = chartWidth – padding.left – padding.right; var plotAreaHeight = chartHeight – padding.top – padding.bottom; // Find max values for scaling var maxValue = purchasePrice; for (var j = 0; j maxValue) maxValue = values[j]; } if (maxValue === 0) maxValue = 100; // Avoid division by zero // Draw background and axes ctx.fillStyle = '#ffffff'; ctx.fillRect(0, 0, chartWidth, chartHeight); ctx.strokeStyle = '#cccccc'; ctx.lineWidth = 1; // Y-axis ctx.beginPath(); ctx.moveTo(padding.left, padding.top); ctx.lineTo(padding.left, chartHeight – padding.bottom); ctx.stroke(); // X-axis ctx.beginPath(); ctx.moveTo(padding.left, chartHeight – padding.bottom); ctx.lineTo(chartWidth – padding.right, chartHeight – padding.bottom); ctx.stroke(); // Y-axis labels and ticks ctx.fillStyle = '#333333'; ctx.textAlign = 'right'; ctx.textBaseline = 'middle'; var numYLabels = 5; for (var k = 0; k <= numYLabels; k++) { var yValue = Math.round(maxValue / numYLabels * k); var yPos = chartHeight – padding.bottom – (yValue / maxValue) * plotAreaHeight; ctx.fillText(formatCurrency(yValue), padding.left – 10, yPos); ctx.beginPath(); ctx.moveTo(padding.left – 5, yPos); ctx.lineTo(padding.left, yPos); ctx.stroke(); } // X-axis labels and ticks ctx.textAlign = 'center'; ctx.textBaseline = 'top'; var numXLabels = labels.length; for (var l = 0; l < labels.length; l++) { var xPos = padding.left + (plotAreaWidth / (numXLabels – 1)) * l; ctx.fillText(labels[l], xPos, chartHeight – padding.bottom + 10); ctx.beginPath(); ctx.moveTo(xPos, chartHeight – padding.bottom); ctx.lineTo(xPos, chartHeight – padding.bottom + 5); ctx.stroke(); } // Draw data series: Total Value ctx.strokeStyle = '#004a99'; // Primary color ctx.lineWidth = 2; ctx.beginPath(); for (var m = 0; m < values.length; m++) { var xPos = padding.left + (plotAreaWidth / (numXLabels – 1)) * m; var yPos = chartHeight – padding.bottom – (values[m] / maxValue) * plotAreaHeight; if (m === 0) { ctx.moveTo(xPos, yPos); } else { ctx.lineTo(xPos, yPos); } } ctx.stroke(); // Draw data series: Interest Earned (as bars) – simplified representation // For simplicity, let's just draw interest earned this year as bars on top of value line ctx.fillStyle = '#28a745'; // Success color for interest ctx.globalAlpha = 0.6; for (var n = 0; n 0 ? tableData[0].year -1 : null)) continue; // Skip baseline for interest bars var xPos = padding.left + (plotAreaWidth / (numXLabels – 1)) * n; var valueYPos = chartHeight – padding.bottom – (values[n] / maxValue) * plotAreaHeight; var interestYPos = chartHeight – padding.bottom – ((values[n] – (n > 0 ? values[n-1] : purchasePrice)) / maxValue) * plotAreaHeight; // Draw bar representing interest earned THIS YEAR var yearInterest = interests[n]; if (yearInterest === undefined) yearInterest = 0; // handle initial year var barHeight = ((yearInterest) / maxValue) * plotAreaHeight; var barTopY = chartHeight – padding.bottom – barHeight; // The interest earned each year is already in tableData[n].interestEarned // We need to plot this relative to the baseline value for that year var yearValue = values[n]; var interestForYear = tableData[n] ? tableData[n].interestEarned : 0; var interestBarTopY = chartHeight – padding.bottom – (interestForYear / maxValue) * plotAreaHeight; var baseValueYPos = chartHeight – padding.bottom – ((values[n] – interestForYear) / maxValue) * plotAreaHeight; // Start of interest bar is end of principal // Redraw interest as bars for clarity var barWidth = (plotAreaWidth / (numXLabels – 1)) * 0.6; // Adjust bar width var barX = xPos – barWidth / 2; // Draw bar for interest earned THIS YEAR var currentYearInterest = tableData[n] ? tableData[n].interestEarned : 0; var interestBarHeight = (currentYearInterest / maxValue) * plotAreaHeight; if (interestBarHeight < 1) interestBarHeight = 1; // Minimum height var barBaseY = chartHeight – padding.bottom; var interestBarTop = barBaseY – interestBarHeight; // Need to plot total value line and interest bars separately } // Redraw total value line ctx.fillStyle = '#ffffff'; // Clear previous drawing ctx.fillRect(0, 0, chartWidth, chartHeight); ctx.strokeStyle = '#cccccc'; ctx.lineWidth = 1; // Redraw axes and labels ctx.beginPath(); ctx.moveTo(padding.left, padding.top); ctx.lineTo(padding.left, chartHeight – padding.bottom); ctx.stroke(); // Y axis ctx.beginPath(); ctx.moveTo(padding.left, chartHeight – padding.bottom); ctx.lineTo(chartWidth – padding.right, chartHeight – padding.bottom); ctx.stroke(); // X axis ctx.fillStyle = '#333333'; ctx.textAlign = 'right'; ctx.textBaseline = 'middle'; for (var k = 0; k <= numYLabels; k++) { var yValue = Math.round(maxValue / numYLabels * k); var yPos = chartHeight – padding.bottom – (yValue / maxValue) * plotAreaHeight; ctx.fillText(formatCurrency(yValue), padding.left – 10, yPos); ctx.beginPath(); ctx.moveTo(padding.left – 5, yPos); ctx.lineTo(padding.left, yPos); ctx.stroke(); } ctx.textAlign = 'center'; ctx.textBaseline = 'top'; for (var l = 0; l < labels.length; l++) { var xPos = padding.left + (plotAreaWidth / (numXLabels – 1)) * l; ctx.fillText(labels[l], xPos, chartHeight – padding.bottom + 10); ctx.beginPath(); ctx.moveTo(xPos, chartHeight – padding.bottom); ctx.lineTo(xPos, chartHeight – padding.bottom + 5); ctx.stroke(); } // Draw Total Value Line ctx.strokeStyle = '#004a99'; ctx.lineWidth = 2; ctx.beginPath(); for (var m = 0; m < values.length; m++) { var xPos = padding.left + (plotAreaWidth / (numXLabels – 1)) * m; var yPos = chartHeight – padding.bottom – (values[m] / maxValue) * plotAreaHeight; if (m === 0) ctx.moveTo(xPos, yPos); else ctx.lineTo(xPos, yPos); } ctx.stroke(); // Draw Interest Earned Bars (for each year) ctx.fillStyle = '#28a745'; ctx.globalAlpha = 0.6; var barWidth = (plotAreaWidth / (numXLabels – 1)) * 0.6; for (var y = 0; y < tableData.length; y++) { var yearIndexInLabels = labels.indexOf(tableData[y].year); if (yearIndexInLabels === -1) continue; var xPos = padding.left + (plotAreaWidth / (numXLabels – 1)) * yearIndexInLabels; var interestEarned = tableData[y].interestEarned; var interestHeight = (interestEarned / maxValue) * plotAreaHeight; if (interestHeight < 1) interestHeight = 1; var barTopY = chartHeight – padding.bottom – interestHeight; var barX = xPos – barWidth / 2; ctx.fillRect(barX, barTopY, barWidth, interestHeight); } ctx.globalAlpha = 1.0; // Reset alpha } function updateTable(tableData) { var tableBody = getElement("bondTable").getElementsByTagName('tbody')[0]; tableBody.innerHTML = ''; // Clear existing rows if (tableData.length === 0) { var row = tableBody.insertRow(); var cell = row.insertCell(0); cell.colSpan = 3; cell.textContent = "No data available for the selected period."; cell.style.textAlign = "center"; return; } for (var i = 0; i < tableData.length; i++) { var row = tableBody.insertRow(); var cellYear = row.insertCell(0); var cellEndValue = row.insertCell(1); var cellInterestEarned = row.insertCell(2); cellYear.textContent = tableData[i].year; cellEndValue.textContent = formatCurrency(tableData[i].endValue); cellInterestEarned.textContent = formatCurrency(tableData[i].interestEarned); } } function copyResults() { var mainResultValue = getElement("mainResultValue").textContent; var totalInterest = getElement("totalInterest").textContent; var nominalInterest = getElement("nominalInterest").textContent; var yearsHeld = getElement("yearsHeld").textContent; var bondType = getElement("bondType").value; var issueDate = getElement("issueDate").value; var calculationDate = getElement("calculationDate").value; var summary = "TreasuryDirect Savings Bond Calculation Summary:\n"; summary += "Bond Type: " + bondType + "\n"; if(issueDate) summary += "Issue Date: " + issueDate + "\n"; if(calculationDate) summary += "Calculation Date: " + calculationDate + "\n"; summary += "Estimated Current Value: " + mainResultValue + "\n"; summary += "Total Accrued Interest: " + totalInterest + "\n"; summary += "Nominal Interest Earned: " + nominalInterest + "\n"; summary += "Years Held: " + yearsHeld + "\n"; // Use a temporary textarea to copy to clipboard var textArea = document.createElement("textarea"); textArea.value = summary; textArea.style.position = "fixed"; textArea.style.left = "-9999px"; document.body.appendChild(textArea); textArea.focus(); textArea.select(); try { document.execCommand('copy'); alert('Results copied to clipboard!'); } catch (e) { alert('Failed to copy results. Please copy manually.'); } document.body.removeChild(textArea); } function resetCalculator() { getElement("denomination").value = "1000"; getElement("purchasePrice").value = "1000"; getElement("issueDate").value = ""; getElement("bondType").value = "EE"; getElement("rate").value = "3"; getElement("fixedRate").value = "0.1"; getElement("calculationDate").value = ""; getElement("mainResultValue").textContent = "$0.00"; getElement("totalInterest").textContent = "$0.00"; getElement("nominalInterest").textContent = "$0.00"; getElement("yearsHeld").textContent = "0"; getElement("bondTable").getElementsByTagName('tbody')[0].innerHTML = ''; var canvas = getElement("bondChart"); if (canvas) { var ctx = canvas.getContext("2d"); ctx.clearRect(0, 0, canvas.width, canvas.height); } clearErrors(); updateBondTypeInputs(); // Ensure related inputs are shown/hidden correctly } function updateBondTypeInputs() { var bondType = getElement("bondType").value; if (bondType === "EE") { getElement("rateGroup").style.display = "none"; getElement("fixedRateGroup").style.display = "none"; } else { // Series I getElement("rateGroup").style.display = "block"; getElement("fixedRateGroup").style.display = "block"; } } // Event listeners for dynamic updates getElement("bondType").addEventListener("change", updateBondTypeInputs); // Initial setup document.addEventListener("DOMContentLoaded", function() { updateBondTypeInputs(); // Set default calculation date to today if not already set by user var today = new Date().toISOString().split('T')[0]; if (!getElement("calculationDate").value) { getElement("calculationDate").value = today; } // Set default issue date to one year ago for illustrative purposes if blank var oneYearAgo = new Date(); oneYearAgo.setFullYear(oneYearAgo.getFullYear() – 1); if (!getElement("issueDate").value) { getElement("issueDate").value = oneYearAgo.toISOString().split('T')[0]; } });

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