This calculator provides an estimate and does not constitute financial advice.
Actual bond values may vary based on specific bond terms and prevailing interest rates.
Consult official TreasuryDirect.gov resources for precise details.
Understanding US Savings Bonds and Their Value
US Savings Bonds are debt securities issued by the U.S. Department of the Treasury. They are considered one of the safest investments available, backed by the full faith and credit of the U.S. government. Savings bonds are designed for individual investors and offer a way to save money while supporting government financing. The two most common types currently issued are Series EE and Series I bonds.
Series EE Bonds
Series EE bonds are issued at face value (e.g., you pay $100 for a $100 bond). They earn a fixed rate of interest over their 30-year maturity period. A key feature of Series EE bonds issued since May 2005 is that they are guaranteed to double in value if held for 20 years, regardless of the interest rate.
Series I Bonds
Series I bonds are designed to protect investors from inflation. Their interest rate is composed of two parts: a fixed rate that remains the same for the life of the bond, and an inflation rate that is adjusted semi-annually based on the Consumer Price Index (CPI). Like Series EE bonds, Series I bonds are issued at face value and have a maximum maturity of 30 years.
How the Calculator Works
This calculator estimates the current value of your savings bond and its potential value at maturity or based on current rates. The calculation involves several factors:
Purchase Price: The amount you paid for the bond.
Purchase Date: Crucial for determining the bond's age and applicable interest rate periods. Savings bonds accrue interest for 30 years.
Bond Series: EE or I bonds have different interest calculation methods.
For Series EE Bonds: The calculator applies the prevailing interest rates applicable to the bond's issue date. For bonds issued after May 2005, it considers the 20-year doubling guarantee. The value grows with simple interest, compounded semi-annually.
For Series I Bonds: The calculator uses a blend of the fixed rate (determined at purchase) and the semi-annual inflation rate. The exact calculation for Series I bonds is complex, as the inflation component changes. This calculator uses representative current rates or historical data for estimation.
Maturity: Savings bonds typically earn interest for 30 years. After 30 years, they stop earning interest and are "matured." The calculator estimates the value at this point or provides an estimate based on current economic conditions if the bond is not yet mature.
Note: This calculator is a simplified tool. For precise, up-to-the-minute information on your specific savings bond, it is best to consult your account on TreasuryDirect.gov or use their official tools.
// Function to get the current year
function getCurrentYear() {
return new Date().getFullYear();
}
// Mock function to simulate fetching interest rates.
// In a real-world application, this would involve API calls or a more robust data source.
// These are simplified representations and may not reflect exact current rates.
function getInterestRate(bondSeries, issueYear, month, year) {
var baseRate = 0;
var inflationRate = 0; // For Series I
if (bondSeries === 'EE') {
if (year >= 2022) baseRate = 0.10; // Example for recent EE
else if (year >= 2005) baseRate = 0.20; // 20-year guarantee
else if (year >= 1980) baseRate = 0.40; // Older rates vary
else baseRate = 0.30; // Very old rates
} else if (bondSeries === 'I') {
// Series I rates are complex: Fixed Rate + Inflation Rate
// For simplicity, we'll use an example composite rate.
// A real calculator would need both fixed and inflation components.
// Example: Assume a fixed rate of 0.0% for recent I bonds and add inflation
var exampleInflation = 0.03; // 3% annual inflation for example
if (year >= 2022) exampleInflation = 0.04; // Higher recent inflation
else if (year >= 2010) exampleInflation = 0.015;
else exampleInflation = 0.02;
baseRate = exampleInflation; // Simplified representation
}
return { base: baseRate, inflation: inflationRate }; // Return structure for both series
}
function calculateSavingsBond() {
var purchasePrice = parseFloat(document.getElementById('purchasePrice').value);
var purchaseDateStr = document.getElementById('purchaseDate').value;
var bondSeries = document.getElementById('bondSeries').value;
var bondValueResultElement = document.getElementById('bondValueResult');
var estimatedMaturityValueElement = document.getElementById('estimatedMaturityValue');
// Clear previous results
bondValueResultElement.textContent = '–';
estimatedMaturityValueElement.textContent = '–';
// Input validation
if (isNaN(purchasePrice) || purchasePrice = 2005) {
// Simplified 20-year doubling: 100% growth in 20 years = ~3.5% compounded annually
// Using a fixed rate based on issue year is more accurate.
// For this example, we'll use the getInterestRate mock.
// A more accurate calculation would track the specific rate schedule.
if (yearsHeld >= 20) {
effectiveRateForEE = 0.035; // Approx. rate for doubling
} else {
// Use the rate from getInterestRate for years < 20
effectiveRateForEE = rateForCalculation / 100; // Assuming rate is in percent
}
} else {
// Older EE bonds had varying rates. Using mock rate.
effectiveRateForEE = rateForCalculation / 100;
}
monthlyRate = effectiveRateForEE / 12; // Semi-annual rate approximation
for (var i = 0; i = 2005) {
// Assuming 20-year doubling guarantee means it will reach 2x purchase price
// And then continue to accrue interest at a variable rate (currently 0.10%)
if (maxMaturityMonths >= 20 * 12) {
valueAtFullMaturity = purchasePrice * 2; // Doubled at 20 years
// Continue accruing interest from month 240 to 360 at the current rate
var remainingMonths = maxMaturityMonths – (20 * 12);
var currentRateForMaturity = getInterestRate('EE', issueYear, issueMonth, getCurrentYear()).base / 100;
var semiAnnualRateForMaturity = currentRateForMaturity / 2; // Approximating semi-annual
for (var i = 0; i < remainingMonths; i++) {
valueAtFullMaturity += valueAtFullMaturity * semiAnnualRateForMaturity;
}
} else { // Less than 20 years to maturity
var rateForMaturityCalc = getInterestRate('EE', issueYear, issueMonth, issueYear + 30).base / 100; // Use rate applicable at issue
var semiAnnualRateForMaturityCalc = rateForMaturityCalc / 2;
for (var i = 0; i < maxMaturityMonths; i++) {
valueAtFullMaturity += valueAtFullMaturity * semiAnnualRateForMaturityCalc;
}
}
} else {
// Older EE bonds – using the mock rate for the full 30 years
var rateForMaturityCalc = getInterestRate('EE', issueYear, issueMonth, issueYear + 30).base / 100;
var semiAnnualRateForMaturityCalc = rateForMaturityCalc / 2;
for (var i = 0; i < maxMaturityMonths; i++) {
valueAtFullMaturity += valueAtFullMaturity * semiAnnualRateForMaturityCalc;
}
}
valueAtFullMaturity = parseFloat(valueAtFullMaturity.toFixed(2));
estimatedMaturityValueElement.textContent = '$' + valueAtFullMaturity.toLocaleString(undefined, { minimumFractionDigits: 2, maximumFractionDigits: 2 });
} else if (bondSeries === 'I') {
// Series I rates are complex: Fixed + Inflation.
// This simplified calculator uses a blended rate approximation.
// A more accurate calculation would need historical CPI data and the fixed rate.
var blendedRate = rateForCalculation / 100; // Using mock rate as blended rate
monthlyRate = blendedRate / 12; // Approximating monthly compounding
for (var i = 0; i < effectiveMonths; i++) {
currentValue += currentValue * monthlyRate;
}
currentValue = parseFloat(currentValue.toFixed(2));
// For Series I, the value at maturity (30 years) will depend on future inflation.
// We'll use the current blended rate as an estimate for the full term.
var estimatedMaturityValue = purchasePrice;
var estimatedMonthlyRateForMaturity = rateForCalculation / 100 / 12;
for (var i = 0; i < maxMaturityMonths; i++) {
estimatedMaturityValue += estimatedMaturityValue * estimatedMonthlyRateForMaturity;
}
estimatedMaturityValue = parseFloat(estimatedMaturityValue.toFixed(2));
estimatedMaturityValueElement.textContent = '$' + estimatedMaturityValue.toLocaleString(undefined, { minimumFractionDigits: 2, maximumFractionDigits: 2 });
}
bondValueResultElement.textContent = '$' + currentValue.toLocaleString(undefined, { minimumFractionDigits: 2, maximumFractionDigits: 2 });
}
// Initialize date input to today if it's empty or invalid
document.addEventListener('DOMContentLoaded', function() {
var dateInput = document.getElementById('purchaseDate');
if (!dateInput.value) {
var today = new Date();
var dd = String(today.getDate()).padStart(2, '0');
var mm = String(today.getMonth() + 1).padStart(2, '0'); // January is 0!
var yyyy = today.getFullYear();
dateInput.value = yyyy + '-' + mm + '-' + dd;
}
});