Savings bonds are a type of U.S. savings bond that are considered a safe, low-risk investment. They are issued by the U.S. Treasury and pay interest over a set period. The value of a savings bond grows over time, and understanding how to calculate its current value is important for financial planning.
This calculator helps you estimate the current redemption value of your U.S. Savings Bonds, specifically Series EE and Series I bonds. The calculation depends on the bond's face value, issue date, and the specific interest accrual rules for each series.
How the Calculation Works
The value of a savings bond is not a simple interest calculation. It accrues interest based on rates set by the U.S. Treasury. The methods for calculating interest differ between Series EE and Series I bonds.
Series EE Bonds:
Series EE bonds earn a fixed rate of interest for the life of the bond. This rate is set at the time of issue and remains the same for the bond's entire 30-year term. The interest is compounded semiannually. For bonds issued on or after May 1, 2005, they are guaranteed to double in value after 20 years.
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 when the bond is issued and remains the same for the life of the bond (30 years). The inflation rate, however, is adjusted every six months based on the Consumer Price Index (CPI). This means the interest earned by Series I bonds can fluctuate.
Important Note: This calculator provides an ESTIMATE. Official redemption values can be obtained directly from TreasuryDirect.gov or by contacting the Bureau of the Fiscal Service. Interest rates change over time and are subject to Treasury regulations.
Key Factors in Savings Bond Valuation:
Face Value: The original amount printed on the bond when it was purchased.
Issue Date: The date the bond was sold and began earning interest. This is crucial as interest rates and accrual periods are tied to this date.
Bond Series (EE or I): Each series has distinct interest accrual rules and rate structures.
Current Interest Rates: The applicable rates set by the Treasury, which can change periodically, especially for Series I bonds.
When to Use This Calculator:
Estimating the current worth of your savings bond portfolio.
Financial planning and understanding the growth of your investments.
Comparing potential returns of savings bonds with other investment options.
function updateInputLabels() {
var bondType = document.getElementById("bondType").value;
var faceValueLabel = document.getElementById("faceValueLabel");
if (bondType === "EE") {
faceValueLabel.innerHTML = "Face Value (e.g., $100, $1000):";
} else { // Series I
faceValueLabel.innerHTML = "Purchase Price (e.g., $25, $500):";
}
}
function calculateBondValue() {
var faceValue = parseFloat(document.getElementById("faceValue").value);
var issueDateStr = document.getElementById("issueDate").value;
var bondType = document.getElementById("bondType").value;
var resultValueElement = document.getElementById("result-value");
// Clear previous result
resultValueElement.textContent = "$0.00";
// — Input Validation —
if (isNaN(faceValue) || faceValue = today) {
alert("Issue date cannot be in the future.");
return;
}
// — Interest Rate Data (Simplified for demonstration – actual rates vary) —
// THIS IS A SIMPLIFIED MODEL. Actual Treasury rates are complex and historical.
// For accurate calculations, refer to TreasuryDirect.gov's official tables.
var interestRates = {
"EE": {
// Example rates – actual rates are fixed at issue and vary by month/year
// These are illustrative and not precise historical data.
"default": 0.03, // A hypothetical default fixed rate
"guarantee20YearDouble": new Date("2005-05-01")
},
"I": {
// Series I rates have a fixed and an inflation component.
// For simplicity, we'll use a placeholder fixed rate and a hypothetical inflation adjustment.
// Actual calculation requires current CPI data.
"fixedRate": 0.00, // Example fixed rate, can be 0
"inflationRateMultiplier": 1.02 // Example: assumes 2% average inflation over time
}
};
var semiannualPeriods = 0;
var currentValue = faceValue;
var currentInterestRate = 0;
// Calculate semiannual periods elapsed
var yearsElapsed = today.getFullYear() – issueDate.getFullYear();
var monthsElapsed = today.getMonth() – issueDate.getMonth();
semiannualPeriods = (yearsElapsed * 12 + monthsElapsed) / 6;
if (semiannualPeriods = interestRates.EE.guarantee20YearDouble) {
if (yearsElapsed >= 20) {
currentValue = faceValue * 2; // Guaranteed to double
} else {
// Approximate accrual: Compounded semiannually at the fixed rate
// This is a simplified accrual, actual EE bonds have specific rate tables.
currentValue = faceValue * Math.pow(1 + (eeRate / 2), semiannualPeriods);
}
} else {
// Bonds issued before May 1, 2005, have different accrual rules.
// This simplified model will apply a generic rate.
currentValue = faceValue * Math.pow(1 + (eeRate / 2), semiannualPeriods);
}
// Cap value at 30 years if applicable for calculation purposes
if (semiannualPeriods > 60) { // 30 years * 2 periods/year
semiannualPeriods = 60;
currentValue = faceValue * Math.pow(1 + (eeRate / 2), semiannualPeriods);
}
} else { // Series I
// Series I Calculation – Simplified
// Fixed Rate + Inflation Rate. This is highly simplified.
// Actual calculation requires fetching current inflation data.
var fixedRate = interestRates.I.fixedRate;
var inflationRate = interestRates.I.inflationRateMultiplier – 1; // Example annual inflation
// Compounding both rates semiannually (simplified)
var semiannualEffectiveRate = Math.pow(1 + fixedRate, 0.5) * Math.pow(interestRates.I.inflationRateMultiplier, 0.5) – 1;
currentValue = faceValue * Math.pow(1 + semiannualEffectiveRate, semiannualPeriods);
}
// Ensure value doesn't exceed maximum maturity (typically 30 years)
// after which interest stops accruing.
if (yearsElapsed >= 30) {
// For calculation purposes, we might cap it or just var it be,
// but it's important to know interest stops.
// The simplified model above implicitly handles this through semiannualPeriods capping.
}
// — Display Result —
// Using toFixed(2) for currency formatting
resultValueElement.textContent = "$" + currentValue.toFixed(2);
}