Right Triangle Calculator

Any two known values — solve the rest of the right triangle.

Hypotenuse (c)
5
Leg a
3
Leg b
4
Angle A
36.87°
Angle B
53.13°
Area
6
Perimeter
12

Angle C is always 90° by definition in a right triangle — that's what makes it "right."

A worked example

Legs of 3 and 4 give a hypotenuse of exactly 5, with angles of about 36.87° and 53.13° — the classic 3-4-5 right triangle.

Frequently asked questions

What makes a right triangle special compared to the general Triangle Calculator?

Knowing one angle is always 90° removes a degree of freedom — only two more pieces of information (rather than three) are needed to fully solve the triangle, which is why this tool only asks for two values.

Which is the hypotenuse?

Always the side directly opposite the 90° angle — it's also always the longest side of a right triangle.