I Bonds Calculator & I Bonds Interest Calculator

About This I Bonds Calculator & I Bonds Interest Calculator

This free Series I Savings Bonds calculator (also an I Bonds interest calculator) helps you estimate the growth of your I Bonds — U.S. government savings bonds that protect your money from inflation. I Bonds are backed by the full faith and credit of the U.S. Treasury, making them one of the safest investments available.

Interest on I Bonds is calculated as a combination of a fixed rate (set when you buy) and a semiannual inflation rate (adjusted every 6 months based on CPI-U). This means your savings grow with inflation — protecting your purchasing power.

What Are Series I Savings Bonds?

I Bonds are low-risk, U.S. government-issued savings bonds designed to protect your money from inflation. Key features:

• Backed by the U.S. Treasury — Risk-free, like FDIC insurance but sovereign
• Inflation-protected — Interest adjusts with CPI, so your money doesn't lose value
• Federal tax deferred — You pay tax only when you cash in, not annually
• State and local tax free — No state or local income tax on I Bond interest
• Purchase limit — $10,000 per person per year electronically via TreasuryDirect

How I Bond Interest Is Calculated

The interest rate on I Bonds is a combined rate:

• Fixed rate — Stays the same for the 30-year life of the bond, set at purchase
• Inflation rate — Adjusted every May 1 and November 1 based on CPI-U
• Combined formula = Fixed rate + (2 × Inflation rate) + (Fixed rate × Inflation rate)
• Interest compounds semiannually — Every 6 months, your earned interest starts earning interest too

I Bond Rules to Know

• Minimum hold period — 1 year before you can cash in at all
• Early withdrawal penalty — If you cash in before 5 years, you lose the last 3 months of interest
• 30-year maturity — I Bonds earn interest for 30 years, then stop
• Where to buy — TreasuryDirect.gov (electronic) or paper bonds with your tax refund

Frequently Asked Questions

What's the current I Bond rate?

I Bond rates change every 6 months (May 1 and November 1). Recent combined rates have ranged from 4-9% depending on inflation. The fixed rate component varies by purchase date. Check TreasuryDirect.gov for the latest official rates.

Are I Bonds a good investment?

I Bonds are excellent for money you want to keep completely safe while beating inflation. They're ideal for emergency funds or conservative savings. They're not for long-term wealth building (stock market historically beats inflation by 5-7% annually), but for capital preservation, they're one of the best options.

Can I lose money on I Bonds?

No! I Bonds can never lose value. Even if inflation goes negative (deflation), the interest rate floor is 0% — your bond's value can't go down. That's what makes them unique: principal protection + inflation protection.

How much can I invest in I Bonds?

The annual purchase limit is $10,000 per person per year in electronic I Bonds via TreasuryDirect. You can also buy up to $5,000 in paper I Bonds using your federal tax refund. So max $15,000 per person per year.

When should I cash in my I Bonds?

Hold at least 5 years to avoid the 3-month interest penalty. After 5 years, you can cash in anytime with no penalty. Some people hold for all 30 years as part of their conservative portfolio. Consider cashing in when interest rates drop significantly or when you need the money for a major expense.

How I Bond Interest Works

I Bonds have a two-part interest rate that changes every 6 months (May 1 and November 1):

• Fixed rate: Set at purchase and stays the same for the 30-year life of the bond. This can be 0% or slightly positive (recently 0.1-0.9%).
• Inflation rate: Adjusted every 6 months based on CPI (Consumer Price Index). This is the variable part that tracks inflation.

The combined rate (fixed + inflation) is what you actually earn. When inflation is high, I Bond rates are high — up to 9.62% in 2022! When inflation is low, rates drop. But the floor is always 0% — you can never lose money.

Interest is compounded semi-annually. Interest earned in the first 6 months gets added to your principal, and then you earn interest on that new, higher principal. This is how your money grows over time.

Why I Bonds Are Unique

I Bonds are one of the only investments in the world that offer all of these benefits at once:

• 100% safe principal — Backed by the full faith and credit of the U.S. government. Your initial investment can never decrease.
• Inflation protection — Your interest rate adjusts with inflation, so your purchasing power stays the same. No other risk-free investment does this.
• Tax advantages — No state or local taxes on I Bond interest. Federal tax is deferred until you cash in the bond. Plus, if you use the money for education expenses, the federal tax may be completely waived.
• No fees — No purchase fees, no management fees, no penalties (after the first 5 years). What you buy is what you get.
• Minimum investment — Start with just $25 for electronic I Bonds. You don't need thousands to start.

Best Strategies for I Bond Investing

Want to make the most of your I Bonds? Here are smart strategies:

• Buy at the right time — I Bond rates reset on May 1 and November 1. If you buy right before a rate reset, you get the old rate for 6 months, then the new rate. Some people wait to buy until they know the new rate.
• Use your tax refund for paper bonds — You can buy up to $5,000 in paper I Bonds with your federal tax refund. This is on top of the $10,000 electronic limit. It's a great way to force yourself to save.
• Spread purchases across family members — The $10,000 limit is per person. A married couple can buy $20,000 per year. You can also buy I Bonds for your children (custodial accounts) to double down.
• Hold for 5+ years — The 3-month interest penalty for cashing in before 5 years is steep. Plan to hold at least 5 years to maximize your returns.
• Use for education savings — If you use I Bond proceeds for qualified higher education expenses, the federal income tax on the interest is completely tax-free. This makes them better than a 529 plan for some families.

Frequently Asked Questions (More Answers)

Are I Bonds worth it in a low-inflation environment?

Yes! Even when inflation is low, I Bonds still have a fixed rate component (usually 0.1-0.9%) plus whatever inflation is. That's still better than a traditional savings account (0.01%) or even a high yield savings account when rates drop. Plus, you get the peace of mind that if inflation spikes again, your rate will jump automatically.

How are I Bonds taxed?

I Bond interest is exempt from state and local income taxes. Federal income tax is deferred — you don't pay it until you cash in the bond. You can choose to pay federal tax annually as the interest accrues, or wait until redemption. If you use the money for qualified education expenses, the federal tax may be completely waived.

Can I buy I Bonds in my IRA?

No — you can't hold I Bonds inside an IRA or 401(k). They're personal investments you buy directly through TreasuryDirect.gov. The tax deferral benefit is already built in, so you don't need an IRA wrapper.

What's the difference between Series I and Series EE bonds?

Series I Bonds are indexed to inflation, so their rate adjusts every 6 months. Series EE Bonds pay a fixed rate (currently around 2.5%) and are guaranteed to double in value after 20 years. I Bonds are better for beating inflation; EE Bonds are better if you want a guaranteed fixed return.

What happens to I Bonds when I die?

I Bonds can be transferred to a beneficiary. You can register I Bonds in "beneficiary" form, which means when you pass away, the bond automatically goes to your named beneficiary without going through probate. They can then cash it in or keep it in their own name.