Bond Calculator
This bond calculator is the overview page for valuing a plain coupon bond from the inputs most investors actually see: face value, stated coupon rate, market price, remaining years, and payment frequency. The result is not just one yield. It solves yield to maturity, rebuilds the bond’s present-value price, lists the cash flows, and adds duration, modified duration, convexity, and simple rate shock estimates. Use it when you want one fixed-income snapshot before moving to the narrower bond price calculator, bond yield calculator, or yield to maturity calculator.
What this calculator measures
A bond is a contract for scheduled payments. Most coupon dates pay interest, and the maturity date pays the last coupon plus the face value. The calculator uses those promised cash flows to answer two questions. First, what annual yield makes the cash flows equal the market price entered in the form? Second, after that yield is solved, how sensitive is the modeled price to a change in yields?
That makes this page a valuation hub rather than a single-purpose coupon tool. If you only need the stated coupon from a payment amount, use the coupon rate calculator. If you only need annual coupon income divided by price, use the bond current yield calculator. Here, the market price is central: the same 5% coupon can be a high-yielding discount bond, a par bond, or a low-yielding premium bond depending on what you pay today.
Formula matched to the calculator
For each period, the coupon is the face value times the annual coupon rate, divided by payments per year:
The calculator rounds years to maturity times payments per year to get the number of coupon periods. It then solves the annual yield that makes this present-value equation equal the market price:
The final cash flow includes the last coupon plus face value. After solving yield, Macaulay duration weights each period by the present value of its cash flow:
Modified duration is:
Example
Use the default inputs: face value $1,000, coupon rate 5%, market price $980, 10 years to maturity, and 2 payments per year. The coupon per period is $25 because $1,000 · 5% ÷ 2 = $25. The calculator rounds 10 · 2 to 20 coupon periods.
It then solves the yield by iteration. The result is a nominal annual yield to maturity of 5.26%. At that yield, the present value of the 19 semiannual $25 coupons plus the final $1,025 payment comes back to $980.00, matching the entered market price. The duration is 7.97 years, modified duration is 7.76, and convexity is 73.1498. The rate-shock estimates show about -7.40% for a one-percentage-point yield increase and 8.13% for a one-percentage-point yield decrease, using the duration-plus-convexity approximation in the form component.
Price-yield relationship
Bond price and yield move inversely because the cash flows are fixed while the discount rate changes. If investors demand a higher yield for the same issuer, maturity, and coupon, the existing cash flows must be priced lower to compete. If market yields fall, older bonds with higher coupons can become more valuable and trade at a premium. The pull toward face value at maturity matters too: a discount bond can earn coupon income plus price accretion, while a premium bond can earn coupons but lose some principal value as maturity approaches.
Duration explains why the inverse relationship is not equally strong for every bond. A long bond with small coupons has more value tied to distant payments, so its price tends to swing more when yields move. A short bond or high-coupon bond returns cash sooner, so its duration is usually lower. Convexity refines the duration estimate because large yield changes are curved, not perfectly linear.
Tips for accurate inputs
- Use the bond’s face value, not the price you paid, in the face value field.
- Match the coupon frequency to the actual indenture or quote convention.
- Enter years remaining, not the original maturity when the bond was issued.
- Treat callable, putable, floating-rate, amortizing, and inflation-linked bonds cautiously because this page assumes scheduled fixed coupons and one face-value repayment.
- Compare the solved YTM with current yield and coupon rate before assuming a discount bond is automatically attractive.
Informational note
This calculator is for education and scenario analysis. Market quotes can include dealer markups, bid-ask spreads, accrued interest, tax effects, credit risk, and call features. Treasury and agency securities, municipal bonds, and corporate bonds also use different quoting conventions. For savings and household planning outside bond valuation, the interest calculator and present value annuity calculator provide more general time-value-of-money context.
Sources
- SEC, Investor Bulletin: Interest Rate Risk — explains how bond prices, interest rates, coupons, and yield to maturity interact.
- TreasuryDirect, Understanding Pricing — describes Treasury marketable security pricing, discounting, and yield concepts.