Quadrilateral Area Calculator — Rectangle, Parallelogram, Trapezoid, Rhombus
Select a quadrilateral type and enter its dimensions to compute the area instantly. Covers rectangles, parallelograms, trapezoids, and rhombuses with the appropriate formula for each.
Shape
units
units
Area = length × width
- 1
Identify sides
a = 10, b = 5 - 2
Area = a × b
10 × 5 = 50
How does this calculator work?
Four quadrilateral area formulas: Rectangle A = l×w; Parallelogram A = base×height (perpendicular); Trapezoid A = ½(a+b)×h; Rhombus A = ½d₁d₂ (diagonals). Always use the perpendicular height for the parallelogram and trapezoid, not the slant side length.
Formula
How this is calculated
A quadrilateral is any four-sided polygon. The four shapes handled here each have a unique area formula based on their defining measurements.
A rectangle uses two adjacent side lengths (length and width): A = l × w. A parallelogram requires the base and the perpendicular height (not the slant side): A = b × h. Failing to use the perpendicular height is the most common mistake — slant height gives the wrong answer. A trapezoid (trapezium) has one pair of parallel sides of lengths a and b; its area is half the sum of those parallel sides multiplied by the perpendicular height between them: A = ½ × (a + b) × h. A rhombus has four equal sides; when you know the two diagonals d₁ and d₂ (which bisect each other at right angles), the area is half their product: A = ½ × d₁ × d₂. The rhombus perimeter is computed from the half-diagonals: side = √((d₁/2)² + (d₂/2)²), perimeter = 4 × side.
Perimeter is reported for the rectangle (2(l+w)) and rhombus (4 × side) where it can be derived from the given inputs. For the parallelogram and trapezoid only the base and height are given, so the slant sides are unknown and the perimeter cannot be computed without additional information.
Frequently asked questions
The perpendicular height h is the true vertical distance between the parallel sides. The slant side s is longer: s = h / sin(angle). The formula A = b × h uses h because area is base × perpendicular height, not base × slant.
A rhombus's two diagonals bisect each other at right angles, dividing the shape into four congruent right triangles. The area of each triangle is ½ × (d₁/2) × (d₂/2), and four of them gives 4 × ½ × (d₁/2) × (d₂/2) = ½d₁d₂.
A trapezoid has exactly one pair of parallel sides (called bases). A parallelogram has two pairs of parallel sides, making opposite sides equal. A rectangle and rhombus are special cases of parallelograms.
Also known as
TG we-Calculate Editorial Team. (2026). Quadrilateral Area Calculator — Rectangle, Parallelogram, Trapezoid, Rhombus [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/area-quadrilateral-calculator
TG we-Calculate Editorial Team. "Quadrilateral Area Calculator — Rectangle, Parallelogram, Trapezoid, Rhombus." TG we-Calculate. 2026. https://we-calculate.com/calculator/area-quadrilateral-calculator.
TG we-Calculate Editorial Team, "Quadrilateral Area Calculator — Rectangle, Parallelogram, Trapezoid, Rhombus," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/area-quadrilateral-calculator
@misc{wecalculate_area_quadrilateral_calculator, title = {Quadrilateral Area Calculator — Rectangle, Parallelogram, Trapezoid, Rhombus}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/area-quadrilateral-calculator}}, year = {2026}, note = {TG we-Calculate} }
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