6-Month T-Bill Calculator
The 6-month T-Bill is the most popular T-Bill duration — a great balance of yield and flexibility. Enter your investment amount and current rate to see exactly what you pay, earn, and your annual return.
💡 A 6-month T-Bill offers one of the best balances between yield and flexibility — which is why it’s the most widely used duration.
This is the amount you get back at maturity. Minimum $100.
Check latest rate → TreasuryDirect.gov
Fixed at 182 days (26 weeks / 6 months) — auctioned every Monday.
How to Calculate 6-Month T-Bill Returns
- Enter your investment amount (face value)
- Apply the discount rate over 182 days
- Calculate the purchase price (face value minus discount)
- Convert your return into an annualized yield
This calculator performs all these steps instantly and shows your exact return.
What is a 6-Month T-Bill?
A 6-month Treasury Bill (also called a 26-week T-Bill) is the most widely purchased T-Bill duration by individual investors. It matures in 182 days and is auctioned every Monday by the U.S. Treasury. You buy it at a discount and receive the full face value at maturity — the difference is your earnings, guaranteed by the U.S. government.
How 6-Month T-Bill Returns Are Calculated (Step-by-Step)
The formula (the calculator does this for you):
- Your profit = Investment × Rate ÷ 100 × 182 ÷ 360
- You pay upfront = Investment − Your profit
- Annual return = (Profit ÷ You pay) × (365 ÷ 182) × 100
Step 1 — Your profit:
$10,000 × 4.5% × (182 ÷ 360) = $227.50
Step 2 — What you pay today:
$10,000 − $227.50 = $9,772.50
Step 3 — Your annual return:
($227.50 ÷ $9,772.50) × (365 ÷ 182) × 100 = 4.67%
The return is slightly above 4.5% because it is calculated on what you actually paid ($9,772.50), not the full $10,000. In 6 months, you pocket $227.50 — then you can roll into a new 26-week bill or cash out.
Why is the 6-Month T-Bill the Most Popular?
The 26-week T-Bill hits the sweet spot between yield and flexibility. It earns more than shorter T-Bills while only locking your money up for 6 months — making it the go-to choice for investors who want a competitive return without committing a full year.
- Higher yield than 4-week and 13-week T-Bills in normal rate conditions
- Only a 6-month commitment — reassess every half year
- Auctioned weekly — easy to buy at any time
- Simple to auto-reinvest on TreasuryDirect for a hands-off approach
6-Month T-Bill vs Other Durations
| Duration | Days | Earnings on $10K at 4.5% | Annualized Yield | Best For |
|---|---|---|---|---|
| 4-Week | 28 | ~$35.00 | ~4.58% | Max flexibility |
| 13-Week | 91 | ~$113.75 | ~4.63% | Quarterly planning |
| 26-Week | 182 | ~$227.50 | ~4.68% | ⭐ Most popular — best balance |
| 52-Week | 364 | ~$455.00 | ~4.71% | Lock in rate for a year |
Need help choosing? Read our Best T-Bill Duration Guide for a full breakdown including how the rate environment affects your choice.
Tax Treatment of 6-Month T-Bills
Earnings from 6-month T-Bills are subject to federal income tax but are exempt from state and local taxes by federal law. In high state-tax states like California (13.3%), this exemption makes a 6-month T-Bill at 4.5% significantly more valuable than a CD at the same rate.
Find your real after-tax yield and the CD rate needed to match your T-Bill.
Rolling Over Your 6-Month T-Bill
When your 6-month T-Bill matures, you can reinvest the full face value into a new one. Rolling over twice gives you a full year of T-Bill returns. On TreasuryDirect, you can enable auto-reinvestment so the rollover happens automatically.
See how much you earn rolling over your 6-month T-Bill for 1–5 years.
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 (FAQ)
Is a 6-month T-Bill a safe investment?
Yes, a 6-month T-Bill is a very safe investment backed by the U.S. government. If held to maturity, it guarantees full repayment with no credit risk.
How much can I earn from a 6-month T-Bill?
You can earn around $200 to $250 on a $10,000 6-month T-Bill depending on the rate. The exact return depends on the current discount rate and is paid at maturity.
Why is the 6-month T-Bill the most popular?
The 6-month T-Bill is popular because it offers a balance between yield and flexibility. It typically earns more than shorter durations while only locking money for six months.
Can I sell a 6-month T-Bill before maturity?
You cannot sell a 6-month T-Bill early on TreasuryDirect, but you can sell it through a brokerage. The price may vary slightly based on current interest rates.