A triangle calculator is a free geometry tool that calculates the area, perimeter, height and all angles of any triangle. Enter any combination of sides and angles and the tool uses trigonometry — including the Sine Rule and Cosine Rule — to find all remaining measurements automatically.
Solve triangle problems for school, college or university geometry and trigonometry assignments.
Calculate roof pitch angles, rafter lengths and triangular land areas for building and architecture.
Calculate proportions for triangular shapes in graphic design, logos and visual compositions.
Triangulation uses triangle calculations for GPS positioning and map reading.
You need at least three values including at least one side length. Knowing all three sides (SSS), two sides and an angle (SAS/SSA), or one side and two angles (AAS/ASA) is sufficient.
Area = ½ × base × height. If you only know the three sides, use Heron's formula: Area = √(s(s−a)(s−b)(s−c)) where s = (a+b+c)/2.
The three interior angles of any triangle always add up to exactly 180 degrees.
Yes — right triangles can be solved using the Pythagorean theorem (a² + b² = c²) and basic trigonometry (sin, cos, tan).