T-Bill vs Bond Calculator (Treasury Bills vs Bonds After-Tax Comparison)

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T-Bills and bonds are both issued by the U.S. government — but they behave very differently. T-Bills return your money in months, while bonds provide income over many years.

💡 T-Bills are better for short-term safety and flexibility, while bonds are better for long-term income — the right choice depends on your time horizon.

How to Compare T-Bills vs Bonds

• Compare short-term T-Bill rates vs long-term bond yields
• Adjust for taxes (both are state-tax exempt)
• Consider your time horizon (months vs years)
• Decide between lump-sum returns vs regular income

This calculator automatically compares all these factors for your situation.

How This Calculator Works

The formula (done automatically for you):

• T-Bill profit = Investment × Rate ÷ 100 × Days ÷ 360
• T-Bill tax = Profit × Federal Rate (state tax exempt for Treasury T-Bills)
• Bond coupon income = Investment × Coupon Rate ÷ 100 × Days ÷ 365
• Bond tax = Income × Federal Rate (state tax exempt for Treasury bonds)
• You keep = Income − All taxes

T-Bill vs Bond — Key Differences That Impact Your Returns

T-Bills vs Bonds — Key Differences Explained

Duration and Interest Rate Risk

This is the biggest practical difference. T-Bills mature in under a year — so even if interest rates rise sharply while you hold one, you get your money back quickly and can reinvest at higher rates. Bonds lock your rate for 10–30 years, and their market value falls when interest rates rise. In 2022, long-term Treasury bonds lost 20–30% of their market value due to rate hikes.

Income Timing

T-Bills pay all earnings at maturity as a lump sum. Treasury bonds pay semi-annual coupon payments — useful for investors who want regular income throughout the year.

When Should You Choose T-Bills Over Bonds?

• You need the money back within a year
• Interest rates are rising — short duration protects you from being locked into a low rate
• You want minimal price volatility — T-Bills barely move in market value
• You are parking cash temporarily between other investments
• You are uncertain about the rate environment — short durations give you flexibility

When Should You Choose Bonds Over T-Bills?

• You want regular income — bonds pay every 6 months
• Interest rates are falling — lock in today's higher rate for 10–30 years
• You are investing for retirement or long-term goals (5+ years)
• You want to balance a stock-heavy portfolio with stable fixed income
• You believe rates will fall significantly — bond prices rise when rates drop

Related Calculators

Learn more: What Are Treasury Bills — Complete Guide  ·  Are T-Bills Worth It?  ·  Best T-Bill Duration Guide

Frequently Asked Questions (FAQ)

What is the difference between T-Bills and Treasury bonds?

T-Bills are short-term investments, while Treasury bonds are long-term investments. T-Bills mature in 4 to 52 weeks and pay no periodic interest, while bonds mature in 10 to 30 years and pay semi-annual interest. T-Bills have lower interest rate risk, while bond prices fluctuate more when rates change.

Are T-Bills safer than bonds?

T-Bills are safer than bonds for short-term investing because they have lower interest rate risk. Both are backed by the U.S. government, but T-Bills mature quickly and are less affected by rate changes. Long-term bonds can lose value if interest rates rise.

Do bonds give better returns than T-Bills?

Bonds usually offer higher returns than T-Bills over the long term. However, in certain market conditions, such as an inverted yield curve, T-Bills can yield more than long-term bonds. Always compare current rates before deciding.

Which should I choose — T-Bills or bonds?

Choose T-Bills for short-term safety and flexibility, and choose bonds for long-term income. T-Bills are better if you need your money within a year, while bonds are better for generating regular income over many years.