Rhombus Area Calculator
Find the area, side length and perimeter of a rhombus from its two diagonals.
How it works
Area = (d₁ · d₂) / 2 · Side = √((d₁/2)² + (d₂/2)²) · Perimeter = 4 · side
A rhombus is a quadrilateral with four equal sides whose diagonals cross at right angles and bisect each other. The area equals half the product of the two diagonals, because they split the shape into four right triangles. Each side is the hypotenuse of one of those triangles, found from the two half-diagonals by the Pythagorean theorem, so the perimeter is four times that side.
Worked example
For diagonals of 6 and 8 units: area = (6 · 8) / 2 = 24 units²; each half-diagonal is 3 and 4, so the side is √(3² + 4²) = 5 units and the perimeter is 4 · 5 = 20 units.
Sources: Rhombus — Wolfram MathWorld
Frequently asked questions
Can I find a rhombus area from its side and an angle?
Yes — area also equals side² × sin(angle). This calculator uses the two diagonals, which are the most commonly measured lengths, but both methods agree.
How are the diagonals related to the side?
The diagonals cross at right angles and bisect each other, so each side is √((d₁/2)² + (d₂/2)²). With diagonals 6 and 8 this gives a side of 5.
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This calculator is for educational purposes. Double-check important results before acting on them.