Trapezoid (Trapezium) Calculator: Area, Median and Perimeter
Enter the two parallel sides and the height. For an isosceles trapezium the sloping sides are found for you; for any other, enter them to get the perimeter.
- Nothing you type is stored
- Free
- No signup
Area
36cm²
- Median (mid-segment)
- 9 cm
- Perimeter
- 28 cm
- Each leg
- 5 cm
Show working
- A = ½ × (a + b) × h = ½ × (12 + 6) × 4 = 36 cm²
- m = (a + b) / 2 = 9 cm
- leg = √(h² + ((a − b)/2)²) = √(4² + 3²) = 5 cm
- P = a + b + c + d = 28 cm
How to use
- Choose isosceles or general.
- Enter the parallel sides a and b and the height (and the legs for a general trapezium).
- Read the area, median and perimeter with steps.
Good to know
NCERT calls this shape a trapezium; in the US it is a trapezoid. Area = ½ × (sum of parallel sides) × height, from NCERT Class 8 mensuration. The median (mid-segment) is (a + b)/2, so area = median × height.
In an isosceles trapezium both legs are equal: leg = √(h² + ((a − b)/2)²). For a general trapezium the legs must fit the height and the difference of the parallel sides; if they cannot, the calculator says so.
Typical uses: land plots with one slanted side, embankments and canal cross-sections, and roofs.
Questions
Is a trapezium the same as a trapezoid?
Yes. India and the UK say trapezium; the US says trapezoid. Both mean a four-sided shape with one pair of parallel sides.
What is the formula for the area of a trapezium?
A = ½ × (a + b) × h, where a and b are the parallel sides and h the distance between them.
How do I find the slanted side?
For an isosceles trapezium, leg = √(h² + ((a − b)/2)²). For example a = 12, b = 6, h = 4 gives legs of 5.
Why can't I get the perimeter?
For a general trapezium you need both slanted sides. Enter them, or choose isosceles if they are equal.
Is anything I enter stored?
No. The calculation runs in your browser and nothing is sent to a server.