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Triangle Area Calculator: Base & Height, Heron's Formula

Calculate triangle area via base & height, Heron's formula, or SAS.

Quick Answer:Choose your calculation method (base & height, Heron's 3 sides, or SAS), input dimensions, and immediately view area and perimeter.

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How to Use the Triangle Area Calculator: Base & Height, Heron's Formula

Area = 0.5 * Base * Height

Standard: 0.5 * b * h. Heron's: sqrt(s*(s-a)*(s-b)*(s-c)). SAS: 0.5 * a * b * sin(C).

Input: b = 10, h = 5

Explanation: 0.5 * 10 * 5 = 25.

Result: 25 sq units

Input: a=3, b=4, c=5 (Heron's)

Explanation: s = (3+4+5)/2 = 6. sqrt(6*3*2*1) = sqrt(36) = 6.

Result: 6.00 sq units

Input: a = 5, b = 8, angle = 30°

Explanation: 0.5 * 5 * 8 * sin(30°) = 20 * 0.5 = 10.

Result: 10.00 sq units

How do you calculate the area of a triangle?▼

The most common formula is Area = 0.5 * base * height.

What is Heron's formula?▼

Heron's formula finds area from 3 sides: Area = √[s(s-a)(s-b)(s-c)], where s is semi-perimeter (a+b+c)/2.

What is the triangle inequality theorem?▼

The sum of the lengths of any two sides of a triangle must be strictly greater than the length of the remaining side.

How do you find the area with two sides and an angle (SAS)?▼

Area = 0.5 * a * b * sin(C), where C is the angle between sides a and b.

What is the area of a right triangle with legs 6 and 8?▼

0.5 * 6 * 8 = 24 square units.

Is this calculation private?▼

Yes, all trigonometry and square roots execute in your browser engine.

Method	Known Values	Area Formula
Base & Height	Base (b), Height (h)	0.5 * b * h
Heron's (SSS)	Three sides (a, b, c)	√[s(s-a)(s-b)(s-c)] where s=(a+b+c)/2
SAS	Two sides (a, b) and included angle (C)	0.5 * a * b * sin(C)

•Entering side lengths that violate the triangle inequality theorem (a + b must be greater than c).
•Using degrees in trigonometric functions without radian conversion.