Triangle Calculator

Calculate the sides, angles, area, perimeter, and other properties of a triangle.

▼ Enter three known values, including at least one side

Side a

Side b

Side c

Angle A

Angle B

Angle C

Angle Unit

Side a —

Side b —

Side c —

Angle A —

Angle B —

Angle C —

Area —

Perimeter —

Semiperimeter —

Triangle Type —

Inradius —

Circumradius —

Median to side a —

Median to side b —

Median to side c —

What Is a Triangle?

A triangle is a polygon with three sides and three interior angles. The three interior angles always add up to 180 degrees.

Triangle Types

Triangles can be classified by their side lengths as equilateral, isosceles, or scalene, and by their angles as right, acute, or obtuse.

Triangle Formulas

This calculator uses mathematical relationships including the Pythagorean theorem, Law of Sines, Law of Cosines, and Heron's formula.

Frequently Asked Questions

How many values do I need to enter?

Enter three known values, including at least one side of the triangle.

What angle units are supported?

You can enter angles in degrees or radians.

What can this calculator calculate?

The calculator can determine missing sides, angles, area, perimeter, semiperimeter, inradius, circumradius, and triangle type.

Disclaimer

This calculator is provided for general mathematical and educational purposes. While we aim to provide accurate results, SmartMyTools does not guarantee that the results are suitable for professional, academic, engineering, construction, or other specialized applications.