Enter the two diagonals, or a side and height, to calculate a rhombus's area and perimeter.
How to Use the Rhombus Calculator
In Diagonals mode, enter both diagonal lengths. In Side & Height mode, enter the side length and the perpendicular height between two parallel sides instead.
Diagonals: area = (d1 × d2) ÷ 2, side = √((d1÷2)² + (d2÷2)²)
Side & Height: area = side × heightA rhombus is a parallelogram with four equal sides, and its diagonals always cross at a right angle and bisect each other — which is exactly why the diagonal formula works: it's really just four identical right triangles (legs d1÷2 and d2÷2) stacked around the center.
Perimeter is the same in either mode once the side length is known: four times the side, since all four sides are equal by definition.