Math

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Trapezoid Calculator.

Calculate area and perimeter from bases, legs, and height.

On-device calculationNo signup
01

Set your values

Results update as you type.

Area: 19.5

Area

0.000000
Perimeter: 21

Perimeter

0.000000
baseA: 8

baseA

0.000000
baseB: 5

baseB

0.000000
legA: 4

legA

0.000000
legB: 4

legB

0.000000
height: 3

height

0.000000

Results update automatically as you type.

Use Cases

Geometry homework and exams

Quickly verify your manual calculations for trapezoid area and perimeter, saving time and reducing errors.

Example: Check your answer for a trapezoid with bases 8 and 12, legs 5 and 6, and height 4.

Construction and design projects

Determine material quantities or dimensions for trapezoidal shapes in landscaping, carpentry, or architecture.

Example: Calculate the area of a trapezoidal garden bed to estimate soil needed.

Frequently Asked Questions

How do I use the trapezoid calculator?
Enter the lengths of Base a, Base b, Leg a, Leg b, and the Height in the input fields. The calculator will compute the area and perimeter of the trapezoid instantly.
What formulas does the trapezoid calculator use?
The area is calculated as (Base a + Base b) / 2 × Height. The perimeter is the sum of all sides: Base a + Base b + Leg a + Leg b.
Can I calculate the area if I only have the bases and height?
Yes, the area only requires the two bases and the height. However, to get the perimeter, you also need the lengths of both legs.

Tips & Common Mistakes

Tips

  • Ensure all measurements are in the same unit (e.g., all in meters or all in feet) before entering them.
  • Double-check that the height is perpendicular to the bases, not the length of a slanted side.
  • For a quick sanity check, the area should be between the areas of rectangles with the shorter and longer base times the height.
  • If you have a trapezoid with equal legs (isosceles), you can still use the same formulas.

Common Mistakes to Avoid

  • Confusing the height with the length of a leg – the height is the vertical distance between the bases.
  • Forgetting to include all four sides when calculating the perimeter.
  • Using inconsistent units (e.g., mixing inches and feet) without converting first.

Last updated: August 13, 2026