## Summary

To calculate the area of a trapezoid in Excel, you can use a standard formula, adapted to for Excel's math operators. In the example shown, the formula in E5, copied down, is:

``````=(B5+C5)/2*D5
``````

which calculates the area of a trapezoid given the length of side a in column B, the length of side b in column C, and the height (h) in column D.

## Generic formula

``=(a+b)/2*h``

## Explanation

In geometry, the area enclosed by a trapezoid is defined by this formula:

where a is the length of side a, b is the length of side b, and h is the height, measured at a right angle to the base. In Excel, the same formula can be represented like this:

``````=(a+b)/2*h
``````

So, for example, to calculate the area of a trapezoid where a is 3, b is 5, and h is 2, you can use a formula like this:

``````=(5+3)/2*2 // returns 8
``````

In the example shown, the goal is to calculate the area for eleven trapezoids where a comes from column B, b is in column C, and h comes from column D. The formula in E5 is:

``````=(B5+C5)/2*D5
``````

As this formula is copied down the table, it calculates a different area at each new row.

Note: The parentheses in this formula are optional and for readability only. In Excel's order of operations, multiplication will occur before division, so the parentheses are unnecessary.

Author

### Dave Bruns

Hi - I'm Dave Bruns, and I run Exceljet with my wife, Lisa. Our goal is to help you work faster in Excel. We create short videos, and clear examples of formulas, functions, pivot tables, conditional formatting, and charts.