Triangle calculator

Enter any three valid constraints — SSS, SAS, or ASA — and get every remaining side, angle, height, the area (Heron’s formula), perimeter, and a to-scale preview.

How to Triangle calculator

1. Step 1. Choose which three values you know (SSS, SAS, or ASA).
2. Step 2. Enter the sides and/or angles.
3. Step 3. Review all angles, sides, heights, area, and perimeter.
4. Step 4. Check the to-scale SVG preview of the solved triangle.

Frequently asked questions

What do SSS, SAS, and ASA mean?

Shorthand for which three measurements are known: Side-Side-Side, Side-Angle-Side, or Angle-Side-Angle — each uniquely determines a triangle.

Why is my triangle invalid?

Sides must satisfy the triangle inequality (each pair sums to more than the third), and angles must total less than 180°. The tool flags violations.

How is the area computed?

Heron’s formula from the three sides, or ½·a·b·sin(C) when an included angle is known — both exact.