Trapezoid Area Calculator Formula

Understand the math behind the trapezoid area calculator. Each variable explained with a worked example.

Formulas Used

Area

area = (base1 + base2) / 2 * h

Median

median = (base1 + base2) / 2

Variables

VariableDescriptionDefault
base1Base 1 (a)10
base2Base 2 (b)6
hHeight4

How It Works

Trapezoid Area

Formula

Area = ((a + b) / 2) × h

Where a and b are the two parallel sides (bases) and h is the perpendicular height between them.

Median (Midsegment)

The median is the segment connecting the midpoints of the two non-parallel sides. Its length equals the average of the two bases: (a + b) / 2.

Worked Example

Trapezoid with bases 10 and 6, height 4.

base1 = 10base2 = 6h = 4
  1. 01Area = ((10 + 6) / 2) × 4
  2. 02= 8 × 4
  3. 03= 32
  4. 04Median = (10 + 6) / 2 = 8

Frequently Asked Questions

What is a trapezoid?

A trapezoid (or trapezium in British English) is a quadrilateral with exactly one pair of parallel sides, called the bases.

How do I find the height of a trapezoid?

The height is the perpendicular distance between the two parallel bases. If you know the area and both bases, h = 2A/(a+b).

What is an isosceles trapezoid?

An isosceles trapezoid has equal-length non-parallel sides (legs). Its base angles are equal and it has a line of symmetry.

Learn More

Guide

How to Calculate Area of Shapes - Complete Guide

Learn how to calculate the area of common shapes including rectangles, triangles, circles, trapezoids, parallelograms, and ellipses with formulas and examples.

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Open Trapezoid Area Calculator