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How Is Treasury Bill Yield Calculated?

The T-Bill calculator: estimate what you'll pay today and earn at maturity.

Short answer

Ethiopian Treasury Bills are purchased below face value. Annualized yield is calculated as ((face value − purchase price) ÷ purchase price) × (365 ÷ tenor days) × 100.

ETB
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Denomination ETB 5,000 per bill · minimum 1 bill. Amount snaps to the nearest multiple.

You invest today
ETB97,231.64
Purchase priceDiscount earned
Face value at maturityETB 100,000
Purchase priceETB 97,231.64
Discount earnedETB 2,768.36
Fee (0.1%)ETB 97.23
Net investmentETB 97,328.87
Net returnETB 2,671.13
Period return 2.74%Annualized 11.01%

What formula does this calculator use?

Two formulas drive every figure shown above — the annualized yield of a discounted bill, and the purchase price implied by a yield:

Annualized yield = ((Face value − Purchase price) ÷ Purchase price) × (365 ÷ Days) × 100
Purchase price = Face value ÷ (1 + Annual yield × Days ÷ 365)

Conventions: this is the true (investment) yield formula, not the bank-discount convention; the day count is fixed at 365 for every tenor; and the "Annualized return" shown is the simple (non-compounded) annualization of your fee-adjusted period return — so with a fee rate set, it lands slightly below the gross yield you entered.

What do the calculator's terms mean?

Face value
What one bill repays at maturity. Bills come in ETB 5,000 face-value denominations.
Purchase price
What you pay today — the face value discounted by the yield over the tenor.
Discount amount
The monetary difference between face value and purchase price. This is your gross return in birr.
Period return
Your net return over the tenor as a percentage of the cash you put in (price plus fees).
Annualized yield
The period return scaled to a 365-day year, for comparing tenors of different lengths. A return on purchase price — not a 'discount rate'.
Brokerage & transaction fees
Charged by your intermediary on top of the purchase price; they reduce your net return.
Net return
Face value received at maturity minus your total outlay (purchase price + fees).

A worked example

Illustrative only, computed by this calculator's own formula: bidding a 12% annual yield on ETB 100,000 of face value for the 91-day tenor means paying about ETB 97,095.13 today — a discount of ETB 2,904.87. Held to maturity (before fees), that is a period return of 2.99%, or 12.00% annualized.

Compare the yield you enter against the latest auction results, read how to choose a tenor and bid, or start from what Treasury Bills are.

Educational estimate only. Actual price, fees, and tax depend on the auction and your licensed intermediary · moneymarket.et