How to Use the Bond Duration & Rate Sensitivity Calculator
Bond prices move in the opposite direction of interest rates: when rates rise, bond prices fall, and when rates fall, prices rise. This calculator takes the face value, coupon rate, years to maturity, and yield to maturity (YTM) to compute the theoretical price, then derives Macaulay duration and modified duration to estimate how much the price would change for a given rate move.
Duration is the weighted-average time to receive a bond's cash flows and doubles as a measure of interest rate sensitivity. A longer maturity or a lower coupon rate produces a longer duration, and a longer duration means the price swings more for the same change in rates.
The estimated price change here is a first-order approximation using modified duration. It tracks the actual price fairly well for small rate moves of a percentage point or two, but for larger moves or bonds with high convexity (curvature in the price-yield relationship), the estimate becomes less precise — treat it as a directional guide rather than an exact figure.
The same logic applies to bond ETFs and funds: those tracking longer-duration indexes gain more when rates fall, but lose more when rates rise. If you're unsure which way rates are headed, holding shorter-duration bonds or funds is a common way to reduce price volatility.
Frequently Asked Questions
Duration measures how much a bond's price reacts to changes in interest rates. A longer duration means a longer maturity or a lower coupon rate, and in either case the price moves more for the same rate change.
It's a first-order approximation using modified duration, so it's fairly accurate for small rate moves but loses accuracy for large moves since it ignores convexity. Use it to gauge direction and rough magnitude, not an exact price.