Enter a base and area, or three side lengths, to calculate a triangle's height (altitude).
How to Use the Triangle Height Calculator
In Base & Area mode, enter a base and the triangle's area to solve for the perpendicular height to that base. In Three Sides mode, enter all three side lengths instead, and the calculator returns the altitude to each of them.
Height, in a triangle, always means the perpendicular distance from one side to the opposite vertex — rearranging the standard area formula isolates it directly:
height = (2 × area) ÷ baseA triangle has three different heights, one per side, and they're rarely equal — a long base pairs with a short altitude and vice versa, since the area they both describe has to come out the same regardless of which side is measured from.
Three Sides mode makes that visible: it finds the area once via Heron's formula, then divides that same area out three different ways — ha = 2×area ÷ a, hb = 2×area ÷ b, hc = 2×area ÷ c — one for the altitude to each side.