Hypotenuse Calculator

Enter two legs, or an angle and a side, to calculate a right triangle's hypotenuse.

How to Use the Hypotenuse Calculator

In Two Legs mode, enter both legs of a right triangle. In Angle & Side mode, enter one acute angle and choose whether the known side is the Opposite or Adjacent leg — either way, the hypotenuse comes out below.

The most direct route is the Pythagorean theorem, which needs both legs and nothing else:

hypotenuse = √(leg a² + leg b²)

But a right triangle's hypotenuse is just as recoverable from a single leg if an angle is known instead, using whichever ratio connects that leg to the hypotenuse:

hypotenuse = opposite ÷ sin(θ)
hypotenuse = adjacent ÷ cos(θ)

Surveying and construction problems tend to hand over an angle and a distance rather than two measured legs — a ladder's angle against a wall and its base distance, say — which is why this calculator keeps both routes rather than assuming the Pythagorean one always applies.