Equilateral Triangle Calculator

What Is a Equilateral Triangle Calculator?

An equilateral triangle has all three sides — and all three angles (60° each) — exactly equal. It's the most symmetrical triangle shape and appears everywhere from road signs to the Triforce. This calculator finds the height, area, and perimeter from just one side length.

How to Use This Equilateral Triangle Calculator

1. Measure one side of the triangle — since all sides are equal, that's all you need.
2. Enter the side length into the field above.
3. Click Calculate to get the height, area, and perimeter.

Formula

• Height = (√3 / 2) × a
• Area = (√3 / 4) × a²
• Perimeter = 3 × a

Worked Example

A warning sign is an equilateral triangle with 30 cm sides. Height = (√3/2) × 30 ≈ 25.98 cm. Area = (√3/4) × 30² ≈ 389.71 cm². Perimeter = 3 × 30 = 90 cm.