What is Heron's formula?

Heron's formula computes triangle area from all three side lengths (a, b, c). First compute the semi-perimeter s = (a+b+c)/2, then Area = √(s(s−a)(s−b)(s−c)). No angles are needed.

What is the SAS method?

SAS stands for Side-Angle-Side. When you know two sides and the angle between them, Area = (1/2) × a × b × sin(C), where C is the included angle in degrees.

What units does the result use?

The result is in the square of whatever unit you enter. If you enter sides in meters, the area is in square meters (m²). The tool does not convert units.

What makes a valid triangle?

For three sides to form a triangle, each side must be less than the sum of the other two (triangle inequality). The tool will warn you if the entered sides cannot form a valid triangle.

Can I use decimal values?

Yes. All inputs accept decimal values such as 3.5 or 12.75. Results are rounded to six significant figures for readability.

Is the included angle measured in degrees or radians?

The SAS method accepts degrees (0–180). The tool converts to radians internally before applying the sine function.

Triangle Area Calculator

Name: Triangle Area Calculator
Availability: InStock
Author: Nham Vu

Calculate triangle area using base & height, three sides (Heron's formula), or two sides with included angle (SAS).

Enter Measurements

Base

Height

Result

Area — square units

Enter values on the left to see the formula and result.

Summary