CalmCalc
MATH

Triangle Calculator

Calculate triangle using side a, side b, side c

Which measurements are known?Choose the three measurements you know. Angles can be entered in degrees or radians.
4 options
TRIANGLE6 m²

SSS · three sides: Solves SSS, SAS, ASA, or AAS triangles with the laws of cosines and sines, then reports every side, angle, area, and perimeter.

Side a
3
Side b
4
Side c
5
Angle A
36.86989765°
Angle B
53.13010235°
Angle C
90°
Area
6
Perimeter
12
Estimate based on the values shown
MethodSolves SSS, SAS, ASA, or AAS triangles with the laws of cosines and sines, then reports every side, angle, area, and perimeter.

Before you use the result

The result depends on the entered values, selected mode, and displayed mathematical assumptions.

EDITORIAL NOTES

Using the Triangle Calculator responsibly

Page-specific guidance based on this calculator’s implemented method, inputs, and known limits.

What this result is useful for

Triangle calculations depend on which sides and angles are known. The selected workflow applies the corresponding geometric relationship and checks whether the supplied measurements can form a valid triangle.

Assumptions and limits

Angles and lengths must use the displayed units, interior angles sum to 180 degrees, and side lengths must satisfy the triangle inequality. Rounded measurements can produce small discrepancies in a solved angle or side.

How to check the result

Check that the longest side is opposite the largest angle and that all solved sides are positive. Recalculate with an independent relationship, such as the angle sum, Pythagorean theorem for a right triangle, or a law of sines/cosines check.

Content review: August 21, 2026
INTERPRET THE RESULTRead the math guideCheck assumptions, limitations and comparison methods →