Comparatively, your bond is now much more attractive. An investor will be willing to pay more than $1,000 to earn 6% rather than 5%. Duration is the tool that helps investors gauge these price fluctuations that are due to interest rate risk. Duration is expressed as a number of years from the purchase date.In simple terms, a bond's duration will determine how its price is affected by interest rate changes. bond's duration will determine how its price is affected by interest rate changes. The reverse is also true. Using the example above, let's assume that when you sell your bond, new bonds are being issued with 5% coupons. Investors can choose between your 6% bond and a new 5% bond.