Type any three of: side a, side b, side c, angle A, angle B, angle C. The calculator solves the missing three values.

For SSS or SAS triangles, we use Law of Cosines. For ASA, AAS, or SSA, we use Law of Sines. The calculator picks the right method automatically.

Get the area (using Herons formula for SSS, 0.5 x b x h for others) and perimeter. The calculator also shows the angles in degrees and radians.

Triangle types: Equilateral (all 60 degrees), isosceles (two equal sides), scalene (no equal sides), right (one 90 degree angle), acute, and obtuse.
Real-world uses: Roof pitch, land surveying, navigation, construction, trigonometry problems, and engineering design all use triangle math.
Law of Sines: a/sin(A) = b/sin(B) = c/sin(C). Useful for AAS and ASA triangles. The Law of Cosines handles SSS and SAS: c^2 = a^2 + b^2 - 2ab cos(C).

For related calculations, try our square footage calculator.

Triangle Calculator

How our triangle calculator works