1-Year T-Bill Calculator
Calculate the exact purchase price, earnings, and annualized yield for a 1-year (52-week, 364-day) Treasury Bill — the longest T-Bill duration and typically the highest yielding. Just enter your face value and current discount rate.
Minimum $100 — T-Bills are sold in $100 increments on TreasuryDirect.
Use the latest 52-week T-Bill auction rate from TreasuryDirect.gov. Auctioned every 4 weeks.
Fixed at 364 days (52 weeks) — note: T-Bills use 364 days, not 365.
What is a 1-Year T-Bill?
A 1-year Treasury Bill (also called a 52-week T-Bill) is the longest available T-Bill duration, maturing in 364 days. It is auctioned every four weeks by the U.S. Treasury and typically offers the highest yield of any T-Bill in normal market conditions. Like all T-Bills, it is sold at a discount and redeemed at full face value at maturity.
1-Year T-Bill Formula
- Discount = Face Value × (Discount Rate / 100) × (364 / 360)
- Purchase Price = Face Value − Discount
- Annualized Yield = (Discount / Purchase Price) × (365 / 364) × 100
Face Value: $10,000 | Duration: 364 days
Discount = $10,000 × 4.5% × (364/360) = $455.00
Purchase Price = $10,000 − $455.00 = $9,545.00
Annualized Yield = ($455 / $9,545) × (365/364) × 100 = ~4.77%
Who Should Use the 1-Year T-Bill?
The 52-week T-Bill is best for investors who are confident they won't need the money for a full year and want to lock in the highest available T-Bill yield.
- Investors who want maximum yield and won't need cash for 12 months
- Locking in high rates when the Fed is expected to cut rates
- Planning for a known future expense exactly one year away
- Investors building a T-Bill ladder — the 52-week is the longest rung
When to Choose 1-Year vs Shorter Durations
| Rate Environment | Best Choice | Reason |
|---|---|---|
| 🔻 Rates Falling | ✅ 52-Week T-Bill | Lock in today's high rate before it drops |
| ➡️ Rates Stable | ✅ 52-Week or 26-Week | Either works — go longer for slightly more yield |
| 🔺 Rates Rising | ❌ Avoid 52-Week | Stay short — reinvest at higher rates every few weeks |
| ❓ Uncertain | ⚖️ T-Bill Ladder | Mix durations to hedge both directions |
Not sure which direction rates are heading? Read our Best T-Bill Duration Guide for a full analysis including the inverted yield curve explained.
1-Year T-Bill vs Other Durations
| Duration | Days | Earnings on $10K at 4.5% | Annualized Yield | Liquidity |
|---|---|---|---|---|
| 4-Week | 28 | ~$35.00 | ~4.58% | ⭐⭐⭐⭐⭐ |
| 13-Week | 91 | ~$113.75 | ~4.63% | ⭐⭐⭐⭐ |
| 26-Week | 182 | ~$227.50 | ~4.68% | ⭐⭐⭐ |
| 52-Week | 364 | ~$455.00 | ~4.77% | ⭐⭐ |
Tax Treatment of 1-Year T-Bills
Like all T-Bills, 1-year T-Bill earnings are subject to federal income tax but are exempt from state and local taxes. Because the 52-week T-Bill generates the largest absolute earnings of any T-Bill duration, the state tax saving is also the largest. In California at 13.3% state tax, you save approximately $60 in state taxes on a $10,000 52-week T-Bill at 4.5% compared to a CD.
Find your real after-tax yield and the CD rate needed to match your T-Bill.
Find the exact CD rate that would beat your 1-year T-Bill after all taxes.
Related Calculators
New to T-Bills? What Are Treasury Bills — Complete Guide · Are T-Bills Worth It? · Best T-Bill Duration Guide
Frequently Asked Questions
Is a 1-year T-Bill a good investment?
Yes — 1-year T-Bills typically offer the highest yield of any T-Bill duration in normal market conditions. They are backed by the U.S. government and carry no credit risk. They are best for investors who won't need their money for a full year.
How much can I earn from a 1-year T-Bill?
At a 4.5% discount rate, a $10,000 1-year T-Bill earns approximately $450 over 364 days, with an annualized yield of about 4.71%. At 5%, you would earn approximately $500 with a yield of about 5.26%.
When should I choose a 1-year T-Bill over shorter durations?
Choose a 1-year T-Bill when interest rates are expected to fall. Locking in today's higher rate for a full year protects your yield even if the Federal Reserve cuts rates. In a falling rate environment, going short means your reinvestment yields get progressively worse.
How often is the 1-year T-Bill auctioned?
The 52-week T-Bill is auctioned every four weeks (monthly) by the U.S. Treasury — less frequently than shorter T-Bills. Check TreasuryDirect.gov for the upcoming auction schedule and results.