What is the simplest triangle area formula?

Area = (base × height) / 2. The height must be perpendicular to the chosen base. This is the most direct formula when you know both values.

What is Heron's formula?

Heron's formula computes area from three side lengths (a, b, c). First calculate the semi-perimeter s = (a + b + c) / 2, then Area = √(s × (s−a) × (s−b) × (s−c)).

When should I use the SAS (two sides and angle) method?

Use SAS when you know two sides and the angle between them. Area = (1/2) × side1 × side2 × sin(angle). The angle must be in degrees.

What units does this calculator use?

The calculator is unit-agnostic. If you enter lengths in meters, the area is in square meters. Use any consistent unit — feet, centimeters, inches — and the result will be in the corresponding square unit.

Can I calculate the area of a right triangle?

Yes. For a right triangle, the two legs serve as base and height, so Area = (leg1 × leg2) / 2. You can also use Heron's formula with all three sides including the hypotenuse.

Why does my triangle produce no result?

For Heron's formula, the three sides must satisfy the triangle inequality: the sum of any two sides must exceed the third. Invalid combinations (e.g., sides 1, 2, 10) do not form a real triangle.

Area of a Triangle Calculator

Calculate triangle area by base & height, three side lengths (Heron's formula), or two sides and the included angle.

Formula Method

Base

units

Height (perpendicular)

units

Enter values on the left to calculate area

Quick Reference Formulas

Base & Height Area = (b × h) / 2

Heron's (SSS) s = (a+b+c)/2 Area = √(s(s-a)(s-b)(s-c))

Two Sides & Angle Area = (1/2) × s1 × s2 × sin(θ)

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Summary

This calculator finds the area of any triangle using whichever measurements you have available. Choose the base and height method for the simplest case, Heron's formula when you know all three side lengths, or the SAS (two sides and included angle) formula when you have two sides and the angle between them. All calculations run instantly in your browser with no data sent to a server.

How it works

Select the formula that matches the measurements you have.
Enter the required values in the input fields.
The area is calculated instantly as you type.
Copy the result or use it in further calculations.

Use cases

Calculate land or floor area with triangular dimensions.
Solve geometry homework involving triangle area.
Verify manually computed triangle area values.
Find triangle area for carpentry, tiling, or construction cuts.
Cross-check CAD or GIS measurements.
Explore how area changes as side lengths vary.

Frequently Asked Questions

Last updated: 2026-05-28 · Reviewed by Nham Vu