8 free online calculators with step-by-step solutions
Pick the right tool for your problem — 2D shapes, 3D solids, proofs, or composite figures.
Start with these essential triangle calculators calculators
Triangles are the simplest closed polygon — three sides, three vertices, and an interior-angle sum of exactly 180°. That simplicity hides a surprising amount of structure: SSS / SAS / ASA / AAS / SSA solve any triangle from three given parts, the Law of Sines and Law of Cosines connect any side to any angle, and Heron's formula returns the area from just the three side lengths (no height needed). The calculators below cover all standard triangle problems — finding sides, angles, area, perimeter, height, medians, and incenter/circumcenter coordinates — for arbitrary, right, isosceles, equilateral, and special-angle (30-60-90, 45-45-90) triangles. Pick the calculator that matches what you know, not what you want to find: the solvers handle the inversion automatically.
This collection has 8 triangle calculators: 3 are tagged Most Popular, 4 are supporting tools, and 1 are advanced calculators for derivations and proofs. The most-used tools include Triangle Solver, Congruent Triangle Calculator, Similar Triangles Calculator.
1 of these calculators support AI Vision: upload a photo of your problem (handwritten, textbook, or whiteboard) and the AI returns the full step-by-step solution. Vision-enabled tools in this category include Triangle Solver.