Equilateral Triangle Calculator
Area, height, perimeter and radii from one side. Results update as you type.
Enter dimensions
Results
Enter your dimensions above and the results appear here.
About the Equilateral Triangle Calculator
The equilateral triangle calculator is a free online tool: area, height, perimeter and radii from one side. Enter side length (a) and the results update instantly, alongside a labelled diagram so you always know which measurement goes where.
Choose your input unit (mm, cm, m, km, in, ft or yd) and optionally show the results in a different one: lengths, areas and volumes are converted correctly. Every answer shows the formula behind it, and the calculation runs in your browser, so nothing is uploaded.
Equilateral Triangle Calculator example
Side length (a) = 6 cmArea = 15.5885 cm²
Perimeter = 18 cm
Height = 5.1962 cm
Inscribed circle radius = 1.7321 cm
Circumscribed circle radius = 3.4641 cmHow to use the Equilateral Triangle Calculator
- Pick the unit your measurements use. All dimensions must share the same unit.
- Enter side length (a). Focus a field to highlight the matching label on the diagram.
- Read the results as you type. The largest card is the main answer; the others are the related measurements.
- Copy a single value, copy everything, or share a link that keeps your inputs.
Equilateral Triangle Calculator FAQ
What formulas does the equilateral triangle calculator use?
A = (√3/4)a²; P = 3a; h = (√3/2)a; r = a√3/6, R = a√3/3.
Can I use different units?
Yes. Pick the input unit and, if you like, a different output unit. Area results are shown in squared units and volumes in cubed units.
Is this equilateral triangle calculator free and private?
Yes. It is free with no sign-up, and calculations happen on your device, so your numbers are never sent to a server.
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