Trapezoid area calculator
Enter the two bases and the height to get the trapezoid area; add the legs if you also want the perimeter.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter base a, base b, height, leg c (optional), leg d (optional) and length unit.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Area = ½ × (a + b) × h, midsegment = (a + b) ÷ 2 and perimeter = a + b + c + d, where a and b are the parallel bases.
Example
Inputs: Base a = 10, Base b = 6, Height = 3, Length unit = Centimeters (cm). Result: Area: 24 cm²; Midsegment: 8 cm.
Limits and caveats
- The height is the perpendicular distance between the bases, not the slanted leg.
- The perimeter is the sum of the lengths you enter; the tool does not check that the legs fit the bases and height.
Questions about this tool
What is the formula for the area of a trapezoid?
Half the sum of the two parallel bases times the height. Bases 10 and 6 with height 3 give an area of 24.
What is the midsegment?
The segment joining the midpoints of the legs. Its length is the average of the bases, and the area equals it times the height.
Does it matter which base I enter first?
No. The formula adds the bases, so the order does not change the result.