Triangle Area Calculator

Calculate triangle area using multiple methods

Formula

Base/Height: ½×b×h; Heron's: √[s(s-a)(s-b)(s-c)] where s=(a+b+c)/2; SAS: ½×a×b×sin(C)

Three common methods. Base/height is simplest. Heron's works with any 3 sides. SAS uses trigonometry with 2 sides and included angle.

How to Calculate Manually

1
Select calculation method
2
Enter required measurements
3
For 3 sides: verify triangle inequality (each side < sum of other two)
4
For SAS: angle must be between 0° and 180°
5
Calculator applies appropriate formula
6
Shows area and intermediate steps

Reference Table

Method	Inputs Needed	Formula	Best For
Base/Height	Base, Height	½×b×h	Right triangles, known altitude
Heron's (3 sides)	3 sides	√[s(s-a)(s-b)(s-c)]	Any triangle, all sides known
SAS	2 sides + angle	½×a×b×sin(C)	Surveying, trigonometry

Triangle Area Calculator: Three Ways to Find Triangle Area

Calculating the area of a triangle is one of the most fundamental geometry problems. Depending on what measurements you have, different formulas apply. This guide covers all three main methods...

Frequently Asked Questions

What are the different ways to calculate triangle area? Base × Height ÷ 2 (when height known). Heron's formula (3 sides known). SAS: ½ × a × b × sin(C) (2 sides + included angle). ASA/AAS also possible with law of sines.: Base × Height ÷ 2 (when height known). Heron's formula (3 sides known). SAS: ½ × a × b × sin(C) (2 sides + included angle). ASA/AAS also possible with law of sines.
What is Heron's formula? For sides a, b, c: s = (a+b+c)/2 (semiperimeter). Area = √[s(s-a)(s-b)(s-c)]. Works for any triangle.: For sides a, b, c: s = (a+b+c)/2 (semiperimeter). Area = √[s(s-a)(s-b)(s-c)]. Works for any triangle.
When do I use which formula? Use base/height for right triangles or when altitude is known. Use Heron's when you know all 3 sides. Use SAS when you know 2 sides and the angle between them.: Use base/height for right triangles or when altitude is known. Use Heron's when you know all 3 sides. Use SAS when you know 2 sides and the angle between them.

Calculator

Formula

Formula

How to Calculate Manually

Reference Table

Triangle Area Calculator: Three Ways to Find Triangle Area

Frequently Asked Questions

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