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Equilateral Triangle Area Calculator.

Calculate area, perimeter, and height from an equilateral triangle side.

On-device calculationNo signup
01

Set your values

Results update as you type.

area: 15.588457 units²

area

0.000000units²
perimeter: 18

perimeter

0.000000
height: 5.196152

height

0.000000

Results update automatically as you type.

Use Cases

Geometry homework and math practice

Quickly verify your manual calculations for equilateral triangle problems, ensuring accuracy in area, perimeter, and height.

Example: Check your answer for a triangle with side length 5 units.

Design and construction planning

Determine the dimensions of equilateral triangular components, such as trusses, tiles, or decorative elements, for material estimation.

Example: Find the area of a triangular garden plot with side length 10 feet.

Frequently Asked Questions

How do I use the Equilateral Triangle Area Calculator?
Enter the side length of your equilateral triangle in the provided field. The calculator will instantly compute the area, perimeter, and height using the standard formulas.
What formulas does the calculator use?
For an equilateral triangle with side length 'a', the area is (√3/4)*a², the perimeter is 3a, and the height is (√3/2)*a. The calculator applies these formulas automatically.
Can I use any unit for the side length?
Yes, you can enter the side length in any unit (e.g., inches, centimeters, meters). The results will be in the same unit squared for area and the same unit for perimeter and height.

Tips & Common Mistakes

Tips

  • Ensure the side length is positive; the calculator assumes a valid triangle.
  • Use consistent units for all measurements to get correct results.
  • For quick estimates, remember that the height is about 0.866 times the side length.
  • Double-check your input if the results seem unexpected; a small error in side length can significantly affect area.

Common Mistakes to Avoid

  • Entering the side length in one unit but expecting results in another without conversion.
  • Confusing the height with the side length when using the area formula.
  • Using the formula for a general triangle instead of the specific equilateral formula.

Last updated: August 13, 2026