Triangle Calculator

Solve any triangle from 3 sides (SSS). Calculate area, perimeter, all angles, and classify by sides/angles. 100% private. Free and privacy-first.

Free Triangle Calculator

Enter three side lengths and instantly get area, perimeter, all three angles, and the triangle's classification by sides and angles. Built on Heron's formula and the Law of Cosines.

Common Uses

Check homework in geometry class
Plan carpentry and tiling layouts
Verify trigonometry exam answers
Quickly classify triangles for design work
Compute roof or ramp dimensions

How It Works

Area uses Heron's formula. Each angle is derived from the Law of Cosines and converted from radians to degrees. The tool also classifies the triangle: equilateral, isosceles, or scalene by sides; acute, right, or obtuse by angles.

Privacy

All math runs locally in your browser. Nothing is uploaded.

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