I Bond Rate Calculator

I Bond Rate Calculator

Understanding Series I Savings Bonds

Series I Savings Bonds, often called I Bonds, are a type of U.S. savings bond that protects your investment from inflation. They earn interest based on a combination of a fixed rate and an inflation rate, which changes every six months. This makes them an attractive option for long-term savings and for preserving purchasing power in an inflationary environment.

How I Bonds Work

Each I Bond has two components that determine its interest rate:

• Fixed Rate: This rate is set when the bond is issued and remains the same for the life of the bond (30 years). It reflects the real return you can expect from the bond. The Treasury sets this rate periodically.
• Inflation Rate: This rate is adjusted every six months based on the Consumer Price Index for all Urban Consumers (CPI-U). It compensates bondholders for inflation. The Treasury announces the new inflation rate on May 1st and November 1st each year.

The combined rate, known as the composite rate, is what your I Bond actually earns. The formula for the composite rate is:

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

It's important to note that the semiannual inflation rate is applied twice a year, and this formula accounts for that compounding.

Key Features and Considerations

• Inflation Protection: I Bonds are designed to keep pace with inflation, meaning your investment's purchasing power is maintained over time.
• Tax Advantages: Interest earned on I Bonds is exempt from state and local income taxes. Federal income tax is deferred until the bond is redeemed or matures. If used for qualified higher education expenses, the interest may also be federal tax-free.
• Maturity: I Bonds earn interest for 30 years.
• Redemption Rules: You must hold an I Bond for at least 12 months. If you redeem it within five years of purchase, you will forfeit the last three months of interest.
• Purchase Limits: Individuals can purchase up to $10,000 in electronic I Bonds per Social Security number per calendar year. Additional paper I Bonds can be purchased using your federal tax refund.

Using the I Bond Rate Calculator

This calculator helps you estimate the potential growth of your I Bond investment. You need to provide:

• Purchase Date: This is crucial because the fixed rate is set at the time of purchase, and the inflation rate is applied based on when the bond was issued.
• Principal Amount: The initial amount you invest in the I Bond.

The calculator will then use the prevailing fixed rate (if known for the purchase date) and the current semiannual inflation rate to project the composite rate and the interest earned over different time periods (6 months, 1 year, 5 years, and 10 years).

Disclaimer: The fixed rates and inflation adjustments are subject to change by the U.S. Treasury. This calculator provides an estimation based on publicly available data and may not reflect future official rates. Always refer to official TreasuryDirect.gov for the most accurate and up-to-date information.

// Placeholder for official fixed rates – you would ideally fetch this or have a lookup table // This is a simplified example and needs to be updated for accuracy. var officialFixedRates = { "2024-05-01": 1.50, "2024-01-01": 1.30, "2023-11-01": 1.30, "2023-05-01": 1.90, "2023-01-01": 0.90, "2022-11-01": 6.48, "2022-05-01": 3.50, "2022-01-01": 1.80, "2021-11-01": 4.30, "2021-05-01": 1.00, "2021-01-01": 0.40, "2020-11-01": 1.00, "2020-05-01": 0.50, "2020-01-01": 0.50, "2019-11-01": 1.10, "2019-05-01": 1.70, "2019-01-01": 0.40, "2018-11-01": 1.60, "2018-05-01": 0.50, "2018-01-01": 0.30, "2017-11-01": 1.00, "2017-05-01": 0.20, "2017-01-01": 0.10, "2016-11-01": 0.30, "2016-05-01": 0.20, "2016-01-01": 0.00, "2015-11-01": 0.00, "2015-05-01": 0.00, "2015-01-01": 0.10, "2014-11-01": 0.10, "2014-05-01": 0.10, "2014-01-01": 0.20, "2013-11-01": 0.20, "2013-05-01": 0.30, "2013-01-01": 0.30, "2012-11-01": 0.50, "2012-05-01": 0.80, "2012-01-01": 0.40, "2011-11-01": 1.00, "2011-05-01": 0.80, "2011-01-01": 1.40, "2010-11-01": 1.60, "2010-05-01": 1.50, "2010-01-01": 1.40, "2009-11-01": 2.00, "2009-05-01": 1.90, "2009-01-01": 0.70, "2008-11-01": 3.30, "2008-05-01": 2.80, "2008-01-01": 2.20, "2007-11-01": 3.00, "2007-05-01": 2.80, "2007-01-01": 2.40, "2006-11-01": 2.90, "2006-05-01": 2.90, "2006-01-01": 3.00, "2005-11-01": 3.00, "2005-05-01": 3.00, "2005-01-01": 3.20, "2004-11-01": 3.30, "2004-05-01": 3.30, "2004-01-01": 3.40, "2003-11-01": 3.60, "2003-05-01": 3.60, "2003-01-01": 3.80, "2002-11-01": 3.90, "2002-05-01": 3.90, "2002-01-01": 3.70 }; // Known semiannual inflation rates (May 1st and November 1st announcements) var semiannualInflationRates = { "2024-05-01": 1.80, // Example: Inflation for May 2024 – April 2025 "2023-11-01": 2.00, // Example: Inflation for Nov 2023 – April 2024 "2023-05-01": 2.90, // Example: Inflation for May 2023 – Oct 2023 "2022-11-01": 4.10, // Example: Inflation for Nov 2022 – April 2023 "2022-05-01": 4.80, // Example: Inflation for May 2022 – Oct 2022 "2021-11-01": 4.30, // Example: Inflation for Nov 2021 – April 2022 "2021-05-01": 1.80, // Example: Inflation for May 2021 – Oct 2021 "2020-11-01": 1.10, // Example: Inflation for Nov 2020 – April 2021 "2020-05-01": 0.60, // Example: Inflation for May 2020 – Oct 2020 "2019-11-01": 1.40, // Example: Inflation for Nov 2019 – April 2020 "2019-05-01": 1.80, // Example: Inflation for May 2019 – Oct 2019 "2018-11-01": 2.20, // Example: Inflation for Nov 2018 – April 2019 "2018-05-01": 1.70, // Example: Inflation for May 2018 – Oct 2018 "2017-11-01": 2.20, // Example: Inflation for Nov 2017 – April 2018 "2017-05-01": 1.00, // Example: Inflation for May 2017 – Oct 2017 "2016-11-01": 1.50, // Example: Inflation for Nov 2016 – April 2017 "2016-05-01": 0.70, // Example: Inflation for May 2016 – Oct 2016 "2015-11-01": 0.50, // Example: Inflation for Nov 2015 – April 2016 "2015-05-01": 0.20, // Example: Inflation for May 2015 – Oct 2015 "2014-11-01": 1.40, // Example: Inflation for Nov 2014 – April 2015 "2014-05-01": 1.40, // Example: Inflation for May 2014 – Oct 2014 "2013-11-01": 1.50, // Example: Inflation for Nov 2013 – April 2014 "2013-05-01": 1.20, // Example: Inflation for May 2013 – Oct 2013 "2012-11-01": 1.90, // Example: Inflation for Nov 2012 – April 2013 "2012-05-01": 2.00, // Example: Inflation for May 2012 – Oct 2012 "2011-11-01": 2.60, // Example: Inflation for Nov 2011 – April 2012 "2011-05-01": 1.60, // Example: Inflation for May 2011 – Oct 2011 "2010-11-01": 1.20, // Example: Inflation for Nov 2010 – April 2011 "2010-05-01": 1.60, // Example: Inflation for May 2010 – Oct 2010 "2009-11-01": 1.90, // Example: Inflation for Nov 2009 – April 2010 "2009-05-01": 0.30, // Example: Inflation for May 2009 – Oct 2009 "2008-11-01": 3.40, // Example: Inflation for Nov 2008 – April 2009 "2008-05-01": 1.60, // Example: Inflation for May 2008 – Oct 2008 "2007-11-01": 1.70, // Example: Inflation for Nov 2007 – April 2008 "2007-05-01": 1.70, // Example: Inflation for May 2007 – Oct 2007 "2006-11-01": 1.90, // Example: Inflation for Nov 2006 – April 2007 "2006-05-01": 1.80, // Example: Inflation for May 2006 – Oct 2006 "2005-11-01": 2.60, // Example: Inflation for Nov 2005 – April 2006 "2005-05-01": 2.60, // Example: Inflation for May 2005 – Oct 2005 "2004-11-01": 3.40, // Example: Inflation for Nov 2004 – April 2005 "2004-05-01": 3.30, // Example: Inflation for May 2004 – Oct 2004 "2003-11-01": 3.40, // Example: Inflation for Nov 2003 – April 2004 "2003-05-01": 1.40, // Example: Inflation for May 2003 – Oct 2003 "2002-11-01": 2.00, // Example: Inflation for Nov 2002 – April 2003 "2002-05-01": 1.40 // Example: Inflation for May 2002 – Oct 2002 }; function getFixedRate(purchaseDate) { // Find the closest preceding announcement date for the fixed rate var announcementDates = Object.keys(officialFixedRates).sort().reverse(); var announcementDate = null; for (var i = 0; i = announcementDates[i]) { announcementDate = announcementDates[i]; break; } } return announcementDate ? officialFixedRates[announcementDate] : null; } function getSemiannualInflationRate(purchaseDate) { // Determine which semiannual inflation rate to use based on purchase date // The rate announced on May 1st applies from May 1st to Oct 31st // The rate announced on Nov 1st applies from Nov 1st to April 30th var purchaseMonth = new Date(purchaseDate).getMonth(); // 0-11 var announcementDates = Object.keys(semiannualInflationRates).sort().reverse(); var relevantAnnouncementDate = null; for (var i = 0; i = 4) { // May is month 4 // Look for the most recent May 1st announcement or later if (annMonth === 4 && annYear <= purchaseYear && (annYear = 1)) { relevantAnnouncementDate = announcementDates[i]; break; } } else { // If purchase date is before May 1st (Jan, Feb, Mar, Apr) // Look for the most recent Nov 1st announcement from the previous year or later if (annMonth === 10 && annYear <= (purchaseYear – 1) && (annYear = 1)) { relevantAnnouncementDate = announcementDates[i]; break; } } } return relevantAnnouncementDate ? semiannualInflationRates[relevantAnnouncementDate] : null; } function calculateCompositeRate(fixedRate, semiannualInflationRate) { if (fixedRate === null || semiannualInflationRate === null) { return null; } var compositeRate = fixedRate + (2 * semiannualInflationRate) + (semiannualInflationRate * fixedRate); return compositeRate; } function calculateIBondRates() { var purchaseDateStr = document.getElementById("purchaseDate").value; var principalAmount = parseFloat(document.getElementById("principalAmount").value); if (!purchaseDateStr || isNaN(principalAmount) || principalAmount <= 0) { alert("Please enter a valid purchase date and principal amount."); return; } var purchaseDate = new Date(purchaseDateStr); var displayPurchaseDate = purchaseDate.toLocaleDateString(); var fixedRate = getFixedRate(purchaseDateStr); var semiannualInflationRate = getSemiannualInflationRate(purchaseDateStr); var compositeRate = calculateCompositeRate(fixedRate, semiannualInflationRate); var inflationRateThroughSixMonths = (semiannualInflationRate !== null) ? (semiannualInflationRate * 2) : 0; // For display purposes, show the annual inflation component var interestEarnedSixMonths = 0; var totalValueSixMonths = principalAmount; var interestEarnedOneYear = 0; var totalValueOneYear = principalAmount; var interestEarnedFiveYears = 0; var totalValueFiveYears = principalAmount; var interestEarnedTenYears = 0; var totalValueTenYears = principalAmount; if (compositeRate !== null) { // Calculate interest for first 6 months var ratePerPeriodSixMonths = compositeRate / 2; // I bonds compound twice a year var interestThisPeriod1 = principalAmount * (ratePerPeriodSixMonths / 100); var valueAfterSixMonths = principalAmount + interestThisPeriod1; interestEarnedSixMonths = interestThisPeriod1; totalValueSixMonths = valueAfterSixMonths; // Calculate interest for 1 year var ratePerPeriodOneYear = compositeRate / 2; var interestThisPeriod2 = valueAfterSixMonths * (ratePerPeriodOneYear / 100); var valueAfterOneYear = valueAfterSixMonths + interestThisPeriod2; interestEarnedOneYear = valueAfterOneYear – principalAmount; totalValueOneYear = valueAfterOneYear; // Calculate interest for 5 years (compounding annually for simplicity here, actual is more complex) var totalValueFiveYears = principalAmount * Math.pow((1 + compositeRate / 100), 5); interestEarnedFiveYears = totalValueFiveYears – principalAmount; // Calculate interest for 10 years (compounding annually for simplicity here) var totalValueTenYears = principalAmount * Math.pow((1 + compositeRate / 100), 10); interestEarnedTenYears = totalValueTenYears – principalAmount; } document.getElementById("displayPurchaseDate").textContent = displayPurchaseDate; document.getElementById("displayPrincipalAmount").textContent = principalAmount.toFixed(2); document.getElementById("displayInflationRate").textContent = inflationRateThroughSixMonths.toFixed(2); document.getElementById("displayFixedRate").textContent = fixedRate !== null ? fixedRate.toFixed(2) : "N/A"; document.getElementById("displayCompositeRate").textContent = compositeRate !== null ? compositeRate.toFixed(2) : "N/A"; document.getElementById("interestEarnedSixMonths").textContent = interestEarnedSixMonths.toFixed(2); document.getElementById("totalValueSixMonths").textContent = totalValueSixMonths.toFixed(2); document.getElementById("interestEarnedOneYear").textContent = interestEarnedOneYear.toFixed(2); document.getElementById("totalValueOneYear").textContent = totalValueOneYear.toFixed(2); document.getElementById("interestEarnedFiveYears").textContent = interestEarnedFiveYears.toFixed(2); document.getElementById("totalValueFiveYears").textContent = totalValueFiveYears.toFixed(2); document.getElementById("interestEarnedTenYears").textContent = interestEarnedTenYears.toFixed(2); document.getElementById("totalValueTenYears").textContent = totalValueTenYears.toFixed(2); }