Area of Trapezoid

Trapezoid Area Calculator

Compute the area of any trapezoid (trapezium) instantly using the standard formula A = ½ × (a + b) × h. Complete with dynamic step-by-step calculation, unit conversion, and visual diagram.

Calculated Area (A)
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Base a (top) Base b (bottom) Height h

How to Calculate the Area of a Trapezoid

A trapezoid (or trapezium in British, Australian, and Indian English) is a 2D quadrilateral with at least one pair of parallel opposite sides, known as bases. The perpendicular distance between these parallel bases is the height ($h$).

The Standard Area Formula

Area = ½ × (a + b) × h = ((a + b) × h) / 2

Where:

  • a = Length of first parallel base
  • b = Length of second parallel base
  • h = Perpendicular height between base a and base b

Step-by-Step Example Calculation

Suppose you have a trapezoid with top base a = 8 cm, bottom base b = 14 cm, and perpendicular height h = 5 cm:

  1. Sum the parallel bases: 8 + 14 = 22 cm
  2. Take the average: 22 ÷ 2 = 11 cm
  3. Multiply by the perpendicular height: 11 × 5 = 55 cm²

The total surface area is 55 square centimeters (cm²).

Full Suite of Solvers

Specialized Trapezoid Calculators

Compute area, perimeter, and missing dimensions for any trapezoid configuration or real-world application.

Frequently Asked Questions About Trapezoid Area

How do you calculate the area of a trapezoid?
To calculate the area of a trapezoid, add the lengths of its two parallel bases, multiply the sum by the perpendicular height, and divide by 2. Formula: Area = ((Base 1 + Base 2) × Height) ÷ 2 Enter both base lengths and the height into the trapezoid area calculator to get your result instantly.
What is the formula for the area of a trapezoid?
The formula for the area of a trapezoid is A = ½(a + b)h, where a and b represent the parallel bases and h represents the perpendicular height. The result is expressed in square units, such as cm², m², or ft².
How do I use a trapezoid area calculator?
Enter the lengths of the two parallel bases and the perpendicular height into the calculator. Select the appropriate measurement units, then calculate the area. The calculator can display the result in square units and show the steps used to obtain it.
What is the difference between a trapezoid and a trapezium?
The terminology depends on the country. In American English, a trapezoid commonly means a quadrilateral with at least one pair of parallel sides. In British English, a trapezium generally refers to a quadrilateral with one pair of parallel sides. Check the definition used by your textbook or course.
How do you find the area of a trapezoid without the height?
You can calculate the area without being given the height directly if you have enough other measurements to determine it. Depending on the shape, these may include the two parallel bases, the non-parallel sides, or suitable angles. Once the perpendicular height is calculated, use the standard trapezoid area formula.
Can you find the area of a trapezoid using its four sides?
Yes, provided the measurements and geometric constraints determine a valid trapezoid. If the two parallel bases and both non-parallel sides are known, the perpendicular height can be calculated when the geometry is valid. The area can then be found using the standard formula.
How do you calculate the area of a right trapezoid?
A right trapezoid has a leg perpendicular to its parallel bases. That perpendicular leg gives the height. Add the two parallel base lengths, multiply the sum by the height, and divide by 2.
How do you find the area of an isosceles trapezoid?
Use the same area formula as for any trapezoid: A = ½(a + b)h. An isosceles trapezoid has equal non-parallel sides. If its two bases and equal side length are known, the height can often be derived from the side length and the difference between the bases, provided the dimensions form a valid shape.
Can you calculate the area of a trapezoid using three sides?
Sometimes. Three side lengths alone do not generally determine the area of an arbitrary trapezoid. However, if the shape has an additional known constraint, such as being a right trapezoid or an isosceles trapezoid, the missing measurement may be calculated.
Can you find the area of a trapezoid using its diagonals?
The area may be determined using the diagonals when sufficient additional information is available, such as the angle between them or other known geometric properties. The two diagonal lengths alone are not generally enough to determine the area of every trapezoid.
What units should I use for trapezoid area?
Use consistent units for all linear measurements. If the bases and height are measured in centimetres, the area is in square centimetres. If they are measured in metres, the area is in square metres. You can convert the final result to another area unit when needed.
How do you calculate the area of a trapezoid in square feet?
Measure both parallel bases and the perpendicular height in feet. Add the bases, multiply their sum by the height, and divide by 2. The answer will be in square feet. If your measurements use different units, convert them to feet first.
How do you calculate the area of a trapezoid in square metres?
Measure both parallel bases and the perpendicular height in metres. Apply the formula A = ½(a + b)h. The resulting area will be in square metres (m²).
What is the area of a trapezoid if its bases are 5 cm and 9 cm and its height is 6 cm?
Add the two bases: 5 + 9 = 14 cm. Multiply by the height: 14 × 6 = 84 cm². Divide by 2 to get an area of 42 cm².
What is the difference between the area of a trapezoid and the volume of a trapezoidal prism?
The area of a trapezoid measures a flat, two-dimensional shape in square units. The volume of a trapezoidal prism measures three-dimensional space in cubic units. To find the prism's volume, multiply the trapezoid's cross-sectional area by the prism's length.