Input Parameters

Find Hypotenuse

Find Leg

Leg A

Leg B

Hypotenuse

Known Leg

Pythagorean Theorem

For any right triangle:
a² + b² = c²
Where:
a, b = lengths of the legs
c = length of the hypotenuse
To find hypotenuse: c = √(a² + b²)
To find a leg: a = √(c² - b²)

Calculation Results

Result

5.00

Hypotenuse of the right triangle

Common Right Triangles

3-4-5 Triangle

5.00

5-12-13 Triangle

13.00

7-24-25 Triangle

25.00

1-1-√2 Triangle (45°)

1.41

Pythagorean Theorem Calculator

Quickly calculate the length of any side of a right triangle using the Pythagorean theorem. Ideal for geometry students, engineers, and construction professionals.

The Pythagorean Theorem Calculator is a simple yet powerful tool that applies the classic mathematical formula: a² + b² = c², where c is the hypotenuse of a right-angled triangle, and a and b are the other two sides.

Key Features

Instant calculation of hypotenuse or missing leg
Supports both metric and imperial units
Handles decimal and whole number inputs
User-friendly interface for quick results
Displays the complete formula and result

How to Use the Calculator

Enter values for any two sides of the triangle
Leave the unknown side field blank
Click “Calculate” to find the missing side
Review the full solution shown with steps

Use Cases

Geometry homework and academic studies
Construction and carpentry applications
Architecture and engineering design
Trigonometry practice and learning

Formula Explained

For a right-angled triangle:

If you're solving for c (hypotenuse):
c = √(a² + b²)
If you're solving for a:
a = √(c² - b²)
If you're solving for b:
b = √(c² - a²)

Tips for Accuracy

Ensure you’re dealing with a right triangle (one angle = 90°)
Double-check which side you are solving for
Use consistent units across all inputs

Conclusion

The Pythagorean Theorem Calculator is a must-have for anyone needing to solve triangle side lengths quickly and accurately. It takes the guesswork out of geometry and helps you visualize relationships between sides.