Equilateral Triangle Calculator

Calculate an equilateral triangle. This is the simplest regular polygon (a polygon with equal sides and angles). Enter one of the known values. Then click calculate.


Enter one of the known values of an equilateral triangle

Side length (a=b=c)
Height (h)
Perimeter (p)
Square (S)
The radius of the circumscribed circle (R)
Radius of the inscribed circle (r)


h = √3/2 * a
р = 3 * а
S = a2 * √3 / 4
R = √3 / 3 * a
r = √3 / 6 * a
All angles are equal to each other and equal to 60°

The side length, height, perimeter and radius have the same unit of measurement (for example, a centimeter), the area has the same unit of measurement squared (for example, a square centimeter).

Perimeter P, area A
Heights ha, hb, hc
Circumscribed circle, inscribed circle
Angles and bisectors
The middle of the side
Perpendicular bisector