First of all, you shouldn’t confuse the financial term “duration ... you would have a choice between two formulas: Macaulay Duration, which is expressed in years, and Modified Duration ...

Launch Excel Create a table or use an existing table Type the formula for ... select Financial from the list box. In the section Select a Function, choose the DURATION function from the list.

And those prices fall as interest rates rise. But by how much? Modified duration is a formula that measures the sensitivity of the valuation change of a security to changes in interest rates.