T-Bill (Treasury Bill) Calculator
Convert a T-bill auction price into its annualised yield (or the reverse), and see your exact maturity amount and post-tax return for 91, 182 and 364-day treasury bills.
T-bill details
Results
| Price per ₹100 | — |
| Face value you receive | — |
| Gain at maturity | — |
| Holding period | — |
| Tax at slab (+4% cess) | — |
| Post-tax gain | — |
| Post-tax annualised yield | — |
Yields use the money-market convention: (gain ÷ price) × (365 ÷ days). Face value shown assumes fractional allotment for simplicity; actual allotment rounds to ₹10,000 lots on RBI Retail Direct.
How T-bill pricing works
Treasury bills don't pay coupons. You buy below ₹100 and redeem at exactly ₹100, so the discount is your interest. The market annualises it on an actual/365 basis:
Yield = (100 − Price) ÷ Price × 365 ÷ Days to maturity
A 91-day bill bought at ₹98.65 earns ₹1.35 on ₹98.65 in 91 days: about 1.37% for the quarter, or roughly 5.49% annualised. Because auctions happen every week, the yield tracks the RBI's repo rate closely. When the repo rate moves, T-bill cut-offs reprice almost immediately, faster than banks reprice FD rates.
Why the post-tax number matters
T-bill gains are taxed at your slab, same as FD interest, so a 30% slab investor nets about 3.85% on a 5.6% T-bill. Against FDs the yields usually land close. T-bills win on sovereign safety and on planning around exact maturity dates; FDs win on premature-withdrawal flexibility. Over longer horizons, where LTCG treatment applies, listed bonds change the math. The FD vs bond post-tax comparison covers that case.
Auction calendar
The RBI auctions 91, 182 and 364-day bills every week (typically Wednesdays, with results the same evening). Retail investors bid non-competitively through RBI Retail Direct and receive the weighted-average price, so there's no cut-off to guess. Full walkthrough: how to buy T-bills in India.
Frequently asked questions
How are T-bill returns taxed?
T-bills are zero-coupon: you buy at a discount and receive face value. The gain is a short-term capital gain taxed at your slab rate (T-bills always mature within a year). No TDS is deducted for resident individuals. Our calculator shows the post-tax yield for your slab.
How do I buy T-bills as a retail investor?
The cheapest route is RBI Retail Direct, a free account with the RBI where you bid non-competitively in weekly auctions (minimum ₹10,000). You automatically receive the weighted-average auction price. Brokers like Zerodha and several OBPP platforms also route T-bill orders. See our step-by-step guide to buying T-bills.
What is the difference between 91, 182 and 364-day T-bills?
Only the tenor. All are sovereign zero-coupon instruments auctioned weekly by the RBI. Longer tenors usually offer slightly higher yields; pick the one matching when you need the money, or ladder all three.
Are T-bills better than a savings account or liquid fund?
T-bills are sovereign risk, safer than any bank deposit, and they typically yield more than savings accounts. Against liquid funds: funds offer instant liquidity but charge an expense ratio and carry marginal credit risk, while T-bills lock money to maturity unless you sell on the exchange. Many investors use both.
Related tools & guides
Educational tool, last reviewed July 2026. Results are estimates based on your inputs and standard market conventions; actual traded prices, taxes and platform charges may differ. Not investment advice; see the disclaimer.