Enter the two parallel bases (a and b), two legs (c and d), and the height (h) of your trapezoid to calculate its area, perimeter, and median (midsegment). You can leave the height blank if you know all four sides — the calculator will derive it automatically for an isosceles trapezoid. Results update as you type, giving you the full geometric breakdown of your trapezoid in one place.
Area
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Perimeter
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Median (Midsegment)
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Height Used
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A trapezoid (also called a trapezium in the UK) is a four-sided polygon with at least one pair of parallel sides. The two parallel sides are called the bases, while the other two sides are called legs. A rectangle is technically a special case of a trapezoid where both pairs of opposite sides are parallel.
The area of a trapezoid is calculated as Area = ½ × (a + b) × h, where a and b are the lengths of the two parallel bases and h is the perpendicular height (altitude) between them. This is equivalent to multiplying the median (midsegment) by the height.
The perimeter is simply the sum of all four sides: P = a + b + c + d, where a and b are the parallel bases and c and d are the two non-parallel legs. No special formula is needed — just add up all four side lengths.
The median (or midsegment) of a trapezoid is the line segment that connects the midpoints of the two legs. Its length equals the average of the two bases: m = (a + b) / 2. Notably, the area of the trapezoid also equals the median multiplied by the height.
If the trapezoid is isosceles (both legs are equal in length, c = d), the height can be calculated from the bases and leg length using h = √(c² − ((b − a) / 2)²). For a general scalene trapezoid, you need additional information such as one of the base angles to determine the height.
An isosceles trapezoid has two legs of equal length (c = d), making it symmetrical about the perpendicular bisector of the bases. A right trapezoid has one leg that is perpendicular to both bases, creating two right angles. Both are special cases of the general trapezoid.
Yes — under the inclusive definition (which most mathematicians use today), a parallelogram qualifies as a trapezoid because it has at least one pair of parallel sides. In fact it has two pairs. However, not every trapezoid is a parallelogram; a trapezoid with only one pair of parallel sides is not a parallelogram.
Yes, all input fields accept decimal values, so you can enter measurements like 3.75 or 12.5 without any issues. The results are displayed rounded to two decimal places for clarity, covering most practical and academic use cases.