Right Triangle Calculator
Find the hypotenuse, area, perimeter and acute angles from two perpendicular legs.
Your result
MATHEnter your values and select calculate.
On this page How it works & practical examples
How to use the Right Triangle Calculator
The two inputs must be the sides that meet at the right angle, not one leg and the hypotenuse. Use the same unit for both. The hypotenuse is opposite the 90-degree angle and is always the longest side. Each acute angle is named by the leg opposite it, so the angle opposite leg A increases as A grows relative to B.
The calculation
Worked example
Perpendicular legs of 3 and 4 units produce a hypotenuse of 5 units, an area of 6 square units and a perimeter of 12 units.
Assumptions and limits
This calculator solves right triangles only. It does not infer whether a measured triangle is actually right-angled. Both legs must be positive. Length and perimeter retain your chosen unit; area uses that unit squared. The output is rounded, so the two displayed acute angles may not sum to exactly 90 at the last decimal place.
Common questions
Can I enter a hypotenuse as one of the inputs?
No. Enter both perpendicular legs. A different formula is needed when one known side is the hypotenuse.
Does the size of the unit matter?
The formula works in any consistent unit, including meters, feet or centimeters. Mixing units changes the answer incorrectly.