Right Triangle Calculator
Solves a right triangle's missing sides, angles, hypotenuse and area from any two known values.
Enter Values
Minimum 0
Minimum 0
Minimum 0
How to use this calculator
- Enter any two of: leg a, leg b, hypotenuse c.
- Read the remaining side, the angles, area and perimeter.
How it works
Pythagoras links the sides (a² + b² = c²); the angles come from the legs (tan A = a ÷ b), and area is ½ × a × b.
Worked example
Legs 3 and 4. Hypotenuse 5, angles 36.9° and 53.1°, area 6.
Common mistakes
- Entering the hypotenuse shorter than a leg — it must be the longest side.
- Using this for non-right triangles — it assumes a 90° angle between the legs.
Frequently asked questions
What do I need to solve a right triangle?
Any two pieces beyond the right angle — two sides, or one side and one acute angle — let you find everything else.
Which rules does it use?
The Pythagorean theorem for sides and basic trigonometry (sine, cosine, tangent) to link sides and angles.
Which two values can I enter?
Any two of the two legs and the hypotenuse — the tool solves the rest. It assumes a right angle between the legs.
Related tools
- Pythagorean Theorem Calculator
- Triangle Area Calculator
- Equilateral Triangle Area Calculator
- Regular Hexagon Area Calculator
- Regular Pentagon Area Calculator
- Regular Polygon Area Calculator
Explore more in Geometry, Shape, Area & Volume.
Cite this tool
Zerdly. (2026). Right Triangle Calculator. Retrieved from https://www.zerdly.com/tools/right-triangle-calculator/
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.