How to use the bond price calculator
The page has two tools. Price values a bond from the yield the market demands. Accrued interest works out the interest a buyer owes the seller when a bond changes hands between coupon dates.
For the price:
- Enter the face value and the coupon rate. Both are printed on the bond or listed in your broker’s bond details. Most US bonds trade in $1,000 units.
- Enter the yield to maturity. This is the market rate for bonds of similar credit quality and maturity, or the yield shown next to the bond’s quote.
- Enter the years to maturity. Decimals price the bond between coupon dates: 7.25 years with semiannual coupons means settlement is halfway through a coupon period.
- Choose the coupon frequency. US Treasuries and most US corporate bonds pay semiannually.
For accrued interest, enter the coupon details and the day count convention, then either the last coupon date and the settlement date (as YYYY-MM-DD) or the number of days since the last coupon. Add the quoted price to see the dirty price you would pay.
The bond price formula
A bond is a series of fixed payments, so its price is the sum of their present values at the market yield:
When settlement falls inside a coupon period, each payment is discounted over k − w periods, where w is the fraction of the current period already elapsed. That gives the dirty price; the clean price subtracts the accrued coupon, F × c ÷ f × w.
Accrued interest itself depends on the day count convention:
Actual/actual: Accrued = F × c ÷ f × Actual days ÷ Actual days in the coupon period
Actual/360: Accrued = F × c × Actual days ÷ 360
Dirty price = Clean price + Accrued interestD30/360 counts every month as 30 days: a day 31 becomes 30, and an end date on the 31st becomes 30 when the start date is the 30th or 31st.
A worked example
A $1,000 bond pays a 5% coupon in two payments a year and matures in 10 years. Similar bonds yield 6%.
Each half-year the bond pays $25.00, 20 payments in all, discounted at 3.00% per half-year. The coupons are worth $371.94 today and the $1,000 repayment $553.68, so the price is $925.61, or 92.561 per 100 of face value. The coupon is below the market yield, so the bond sells at a discount of $74.39.
Now suppose you buy a bond like this between coupon dates. The last coupon was paid on 2026-04-15 and the trade settles on 2026-07-31. Under 30/360 that is 106 days of a 180-day period, so the seller has earned $14.72 of the next coupon. At a quoted price of 98.5 per 100, you pay $985.00 plus that interest: a dirty price of $999.72.
Premium, par and discount
The price of a bond depends on how its coupon compares with the yield the market wants:
| Market yield | Price of the 5% bond | Trades at |
|---|---|---|
| 4% | $1,081.76 | A premium |
| 5% | $1,000.00 | Par |
| 6% | $925.61 | A discount |
| 7% | $857.88 | A deeper discount |
When the coupon matches the yield, the bond is worth exactly its face value. A premium bond pays more income than the market requires and gives part of it back as the price falls to par by maturity; a discount bond pays less income and makes up the difference as the price rises to par. This drift toward face value is called the pull to par, and it happens whether or not yields move.
What moves the price most
Maturity matters most. The further away the repayment, the more each change in yield is multiplied:
| Maturity (5% coupon, 6% yield) | Price | If yield rises 1 point | If yield falls 1 point |
|---|---|---|---|
| 2 years | $981.41 | -1.85% | +1.89% |
| 10 years | $925.61 | -7.32% | +8.04% |
| 30 years | $861.62 | -12.89% | +16.06% |
Two things stand out. Long bonds move many times more than short ones for the same change in yield. And in every row the gain from a fall in yield is larger than the loss from an equal rise: the price–yield curve in the chart is convex. Our bond duration calculator measures both effects precisely.
The coupon frequency has a smaller effect. With annual instead of semiannual coupons, the example bond is worth $926.40 at the same quoted yield instead of $925.61. Two forces pull in opposite directions: the coupons arrive later, which lowers the value, but a 6% yield compounded once a year is a lower effective rate than 6% compounded twice, which raises it. When you compare bonds with different coupon frequencies, compare their effective annual yields.
Clean prices, dirty prices and day counts
Bond prices are quoted clean so that the quote does not jump each time a coupon is paid. The money that changes hands is the dirty price. If the example bond had 7.25 years left, the clean price would be $941.81 and the buyer would also pay $12.50 of accrued interest, for $954.31 in total.
The day count convention changes accrued interest by small but real amounts. For the dates in the example, 30/360 gives $14.72, actual/actual gives $14.62 and actual/360 gives $14.86. On a large trade, the convention is worth checking against the trade confirmation.
What this calculator does not include
- Calls, puts and sinking funds. The price assumes the bond runs to maturity. For callable bonds, our bond yield calculator shows the yield to call.
- Credit risk. The yield you enter must already reflect the issuer’s credit quality. Default and recovery are not modeled.
- Business-day adjustments and odd first or last coupons. Coupon dates are assumed to fall on the same day of the month, cut back to the month’s last day where needed. Ex-dividend periods used in some markets outside the US are ignored.
- Taxes and trading costs, including the dealer markup built into most retail bond prices.
- The February end-of-month rules that some versions of 30/360 apply.
For an actual trade, the dealer’s confirmation shows the clean price, accrued interest and total amount due. Use this calculator to check those figures and to see how the price would change at other yields.