Triangle Calculator
Area and basic relations from base and height.
Guide: Triangle Calculator
Triangle area equals one-half times base times height when you know the perpendicular height. For other configurations, you may need Heron’s formula or trigonometry. Triangles appear everywhere in graphics, surveying, and truss design because three constraints (sides, angles, or mix) often fix the shape up to congruence.
When height is not obvious
If you only know side lengths, Heron’s formula can compute area. If you know two sides and the included angle, use (1/2)ab sin(C).
Right triangles shortcut height as one leg when the other leg is the base.
Units consistency
Area inherits square units from length inputs. Mixing meters and centimeters without converting first inflates area by a factor of 100².
Why half base times height
Duplicating the triangle forms a parallelogram with area base × height; your triangle is exactly half of that parallelogram.