Triangle Calculator

Use this Triangle Calculator to find the area and perimeter of a triangle. Change values using keyboard arrows or mouse and get instant results.

Triangle Calculator – Area and Perimeter

A triangle calculator is a geometry tool used to find the area and perimeter of a triangle based on the values you know. This calculator supports multiple calculation methods, making it useful for students, teachers, engineers, and professionals.

What Is a Triangle?

A triangle is a polygon with three sides and three interior angles. The sum of the interior angles of any triangle is always 180 degrees. Triangles are one of the most fundamental shapes in geometry and are widely used in construction, engineering, trigonometry, and design.

Triangle Calculation Methods

  • Three Sides (SSS): Calculates area using Heron’s formula when all sides are known.
  • Base and Height: The simplest method to find triangle area using perpendicular height.
  • Two Sides and Angle (SAS): Uses trigonometry to calculate area when an included angle is given.

Triangle Area and Perimeter Formulas

  • Heron’s Formula:
    Area = √[s(s − a)(s − b)(s − c)], where s = (a + b + c) / 2
  • Base & Height Formula:
    Area = ½ × base × height
  • SAS Formula:
    Area = ½ × a × b × sin(angle)
  • Perimeter Formula:
    Perimeter = a + b + c

Where Triangle Calculations Are Used

  • School and college mathematics problems
  • Engineering and architectural design
  • Land measurement and construction planning
  • Trigonometry and physics calculations

Frequently Asked Questions

The area of a triangle can be calculated using different formulas depending on the known values. The most common formula is Area = ½ × base × height. If all three sides are known, Heron’s formula is used.
Heron’s formula is used to calculate the area of a triangle when all three sides are known. It is given by: Area = √[s(s − a)(s − b)(s − c)], where s is the semi-perimeter.
Yes. This calculator works for scalene, isosceles, and equilateral triangles, as long as valid dimensions are provided.
Units are optional. The calculator works with numbers only, so results can be interpreted in any consistent unit such as cm, meters, or inches.
Yes. All numeric input fields support up and down arrow keys for fine adjustments.