Formula
Area = (√3/4) × s²
Enter value to calculate
Triangle Area
Equilateral Triangle Area Calculator
This calculator computes the area, side length, height, and perimeter of an equilateral triangle using three different input methods. An equilateral triangle has all three sides of equal length and all interior angles of 60°.
The calculator supports multiple measurement units including millimeters, centimeters, meters, kilometers, inches, and feet for linear measurements, with corresponding square units for area calculations.
Key Formulas
Area = (√3/4) × s2
Height = (√3/2) × s
Perimeter = 3 × s
Side from Area: s = √(4A/√3)
The calculator provides three calculation modes: forward calculation from side length or height to find area, and reverse calculation from area to determine all triangle parameters including side length, height, and perimeter.
Calculation Examples
Input: Side length = 10 cm
Output: Area = 43.30 cm2
Input: Height = 8.66 m
Output: Area = 43.30 m2
Input: Area = 100 ft2
Output: Side = 15.20 ft, Height = 13.16 ft
Input: Side length = 25 mm
Output: Area = 270.63 mm2
Input: Height = 2.5 in
Output: Area = 3.61 in2
Input: Area = 50 m2
Output: Perimeter = 32.28 m
Input: Side length = 1.5 km
Output: Area = 0.97 km2
Input: Height = 12 ft
Output: Area = 83.14 ft2
Input: Area = 75 cm2
Output: Side = 13.16 cm, Height = 11.40 cm
Input: Side length = 6 in
Output: Area = 15.59 in2, Perimeter = 18 in
The calculator includes precision controls for decimal places (0-6) and thousands separators (comma, space, or none) to format results according to your preferences. Unit conversion is automatic between metric and imperial systems.