Calculate the area, perimeter, height, and interior angles of an equilateral triangle from a single side length.
An Equilateral Triangle Calculator is a geometry tool designed to calculate the important measurements of an equilateral triangle from one known side length.
An equilateral triangle has three sides of exactly the same length. It also has three equal interior angles, with each angle measuring 60 degrees.
Once you enter the length of one side, this calculator determines the triangle's height, area, perimeter, and interior angles automatically.
Using the calculator is simple. You only need one measurement because all three sides of an equilateral triangle are equal.
Enter the length of one side of your equilateral triangle.
Click the calculate button to process the triangle measurements.
View the height, area, perimeter, and angles in the results section.
The height of an equilateral triangle can be found by dividing the triangle into two right triangles.
The area is calculated using the square of the side length multiplied by √3 divided by 4.
Since all three sides are equal, the perimeter is simply three times the side length.
Every interior angle of an equilateral triangle measures exactly 60 degrees.
An equilateral triangle is a special type of triangle in which all three sides have equal lengths. This equality also makes all three interior angles equal.
The three interior angles add up to 180 degrees. Because the angles are equal, each angle is exactly 60 degrees.
The altitude, median, angle bisector, and perpendicular bisector drawn from any vertex all lie along the same line in an equilateral triangle.
The symmetry of an equilateral triangle makes it useful in geometry, engineering, architecture, design, and many mathematical applications.
Suppose each side of an equilateral triangle is 10 units long.
The area is:
The perimeter is:
Each interior angle remains 60 degrees regardless of the size of the triangle.
An equilateral triangle is a triangle with three equal sides and three equal interior angles. Each interior angle measures 60 degrees.
Multiply the square of the side length by √3 and divide the result by 4. The formula is Area = (√3 / 4) × a².
The height is calculated using Height = (√3 / 2) × a, where a represents the length of any side.
Since all three sides are equal, the perimeter is three times the side length: P = 3a.
All three interior angles are exactly 60 degrees. Their total is therefore 180 degrees.
No. You only need one side length because all three sides of an equilateral triangle are equal.
Yes. The calculator accepts decimal values such as 5.5, 12.75, or 20.25.
You can use any consistent unit. For example, if the side is entered in centimeters, the height and perimeter are in centimeters and the area is in square centimeters.
Yes. An equilateral triangle has at least two equal sides, so it also satisfies the definition of an isosceles triangle.