---
title: "Triangle solver — free, runs in your browser"
description: "Solve any triangle from three known values, with area, perimeter and all angles. Free, no sign-up, and nothing you enter leaves your browser."
url: https://atoneplace.net/tools/triangle-calculator/
site: "At One Place"
---

# Triangle solver

Solve any triangle from three known values, with area, perimeter and all angles.

## How it works

Give three values — three sides, two sides and an angle, or two angles and a side — and this finds the rest, plus area, perimeter and the triangle type.

Three sides always determine a triangle uniquely, which is why triangulation works and why a triangular frame is rigid while a rectangular one racks.

Two sides and a non-included angle is the case that can be ambiguous. Depending on the numbers there may be two valid triangles, one, or none — the so-called SSA case. Where two exist the tool reports both rather than silently picking one.

The triangle inequality is checked first: any side must be shorter than the sum of the other two, or no triangle exists at all.

> This tool runs entirely in your browser. Nothing you enter is sent to a server, logged or stored, and the page keeps working with the network disconnected.

## Common questions

### Can any three lengths form a triangle?

No. Each side must be shorter than the sum of the other two. Three lengths failing that describe no triangle.

### Why is SSA ambiguous?

Two sides and a non-included angle can sometimes be satisfied by two different triangles. Both are valid, which is why the case needs care.

## Related pages

- [Percentage calculator](https://atoneplace.net/tools/percentage-calculator/)
- [Loan and EMI calculator](https://atoneplace.net/tools/loan-calculator/)
- [BMI calculator](https://atoneplace.net/tools/bmi-calculator/)
- [Tip calculator](https://atoneplace.net/tools/tip-calculator/)
- [Age calculator](https://atoneplace.net/tools/age-calculator/)
- [Paint calculator](https://atoneplace.net/tools/paint-calculator/)
- [Compound interest calculator](https://atoneplace.net/tools/compound-interest-calculator/)
- [Calorie and BMR calculator](https://atoneplace.net/tools/calorie-calculator/)
- [Dog age calculator](https://atoneplace.net/tools/dog-age-calculator/)
- [Discount calculator](https://atoneplace.net/tools/discount-calculator/)

## Sources

- Calculated on this page — At One Place (/about/)