Trapezoid Area Calculator
Calculate the area of a trapezoid from its parallel sides and height.
Area of the trapezoid
A trapezoid has one pair of parallel sides, and its area comes from those two parallel sides and the height between them. This calculates it, a common need in geometry, construction and land measurement.
Enter the parallel sides and height to find the area.
The average-width idea
The trapezoid area formula has a genuinely intuitive heart: take the average of the two parallel sides, and multiply by the height. Averaging the two parallel lengths is like straightening the sloped shape into a rectangle of that average width, whose area is simply width times height. This makes the formula something you can understand and reconstruct rather than memorise. It also elegantly contains the rectangle and triangle as special cases — when the parallel sides are equal it becomes a rectangle, and when one shrinks to nothing it becomes a triangle. Trapezoids turn up constantly in real measurement, from irregular plots of land to the cross-sections of ditches and embankments, and this same average-width idea is the basis of a technique in calculus for estimating the area under a curve by slicing it into thin trapezoids.
Frequently asked questions
How is a trapezoid's area calculated?
Average the two parallel sides and multiply by the height — like straightening the shape into a rectangle of that average width.
How does it relate to rectangles and triangles?
When the parallel sides are equal it becomes a rectangle, and when one shrinks to nothing it becomes a triangle — both are special cases.
Is anything uploaded?
No. The calculation happens in your browser.