Equilateral Triangle Calculator
Compute all properties of an equilateral triangle from one side length.
About Equilateral Triangle Calculator
All sides and angles of an equilateral triangle are equal (60° each). Its area, height, inradius and circumradius are all derived from the single side length.
Formulas
Area
A = (√3/4) × s²
- s
- Side length
Height
h = (√3/2) × s
- s
- Side length
Worked example
With the default values below, Equilateral Triangle Calculator returns Area of 43.3013. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Side Lengthminimum 0 units
- 10 units
Results
- Area
- 43.3013 sq units
- Perimeter
- 30.0000 units
- Height
- 8.6603 units
- Inradius
- 2.8868 units
- Circumradius
- 5.7735 units
Step by step
- 1Area= 43.3013
- 2Height= 8.6603
- 3Perimeter= 30
Assumptions and limits
- The result is derived only from the single input listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
Are all equilateral triangles similar?
Yes — all equilateral triangles are similar because they all have three 60° angles. They differ only in scale.
What is the relationship between inradius and circumradius?
For an equilateral triangle, the circumradius is exactly twice the inradius: R = 2r.