This free online right triangle calculator solves for the hypotenuse, area, perimeter, and both acute angles when you know the two legs of a right triangle. Enter side a and side b to get a complete breakdown of your triangle's measurements instantly.
How to Use the Right Triangle Calculator
Enter the length of "Side a" in the first input field.
Enter the length of "Side b" in the second input field.
Click "Calculate" to compute all triangle measurements.
Review the hypotenuse, area, perimeter, and angles in the results table.
Frequently Asked Questions
It calculates the hypotenuse with c = √(a² + b²), area = (a × b) / 2, perimeter = a + b + c, angle A = atan(a/b) converted to degrees, and angle B = 90° - angle A.
Both sides must be positive numbers greater than zero. If either is zero, negative, or left blank, the calculator shows "Please enter valid positive numbers for side a and side b" instead of a result.
For side a = 3 and side b = 4, the hypotenuse is 5, the area is (3×4)/2 = 6, the perimeter is 3+4+5 = 12, angle A ≈ 36.87°, and angle B ≈ 53.13°.
Yes, since this calculator assumes a right triangle where side a and side b form the right angle, angle C is always fixed at 90°.