Pythagoras Theorem Calculator – Find Hypotenuse & Triangle Sides

Calculate the missing side of a right triangle using the Pythagorean theorem (a² + b² = c²)

Pythagoras Theorem Calculator Tool
Select what you want to find and enter the known values to calculate using a² + b² = c²
bac(base)(height)(hypotenuse)

Pythagorean Theorem:

In a right triangle: a² + b² = c²

Where c is the hypotenuse (longest side opposite the right angle)

Formulas:

  • Find hypotenuse: c = √(a² + b²)
  • Find side a: a = √(c² - b²)
  • Find side b: b = √(c² - a²)

Applications:

  • Construction and carpentry
  • Navigation and distance calculations
  • Architecture and design
  • Geometry and trigonometry problems
  • Engineering calculations

Understand the relationship between the sides of a right-angled triangle effortlessly with our Pythagoras Theorem Calculator. Whether you’re a student learning geometry, a teacher preparing exercises, or a professional working on design and measurement, this calculator delivers instant and accurate results. With Digital Calculator, solving for the hypotenuse or missing side of a triangle is simpler than ever.

What Is the Pythagoras Theorem?

The Pythagoras theorem is one of the most fundamental principles in geometry. It describes the relationship between the three sides of a right-angled triangle — where one angle is exactly 90 degrees. The theorem states that:

The square of the hypotenuse (the longest side) is equal to the sum of the squares of the other two sides.

Mathematically, this relationship is expressed as:

a² + b² = c²

Where:

  • a = one leg (base)
  • b = the other leg (height) 
  • c = hypotenuse (the side opposite the right angle)
     

This equation allows you to find any missing side of a right-angled triangle, provided you know the lengths of the other two.

The Formula Explained

Let’s break down the formula step by step.

  1. Start with the equation:
    a² + b² = c²
     
  2. If you want to find the hypotenuse (c), rearrange the formula as:
    c = √(a² + b²)
     
  3. To find one of the shorter sides (a or b), rearrange as:
    a = √(c² - b²) or b = √(c² - a²) 

This simple relationship forms the basis of trigonometry, geometry, and even real-world applications such as engineering, architecture, navigation, and physics.

How to Use the Pythagoras Theorem Calculator

Our Pythagoras Theorem Calculator is designed for ease of use and accuracy. Here’s how you can use it effectively:

  1. Select which side to calculate hypotenuse, base, or height.
  2. Enter the known values for the other two sides.
  3. Click “Calculate.”
    The tool instantly computes the missing side using the Pythagoras formula. 
  4. View results displayed with clear precision, including units if provided.
  5. You can also reset the calculator to try multiple examples or verify classroom exercises quickly.

Example Calculations

Let’s look at some examples to understand how the theorem and calculator work in practice.

Example 1: Finding the Hypotenuse

Suppose you have a right-angled triangle where:

  • a = 3 units
  • b = 4 units 

Find the hypotenuse (c).

Using the formula:

c² = a² + b²
c² = 3² + 4²
c² = 9 + 16
c² = 25
c = √25
c = 5 units

Result: The hypotenuse is 5 units.

Example 2: Finding a Missing Side

Suppose you know the hypotenuse and one side:

  • c = 13 units 
  • b = 5 units 

Find the missing side (a).

a² = c² - b²
a² = 13² - 5²
a² = 169 - 25
a² = 144
a = √144
a = 12 units

Result: The missing side is 12 units.

Example 3: Real-Life Application

You’re setting up a ladder against a wall. The bottom of the ladder is 6 feet away from the wall, and the ladder reaches 8 feet up the wall. What is the length of the ladder?

Using the theorem:

c² = 6² + 8²
c² = 36 + 64
c² = 100
c = √100
c = 10 feet

Result: The ladder must be 10 feet long.

Pythagorean Triples

Pythagorean triple is a set of three positive integers (a, b, c) that satisfy the Pythagorean theorem exactly.

Here are some common examples:

a

b

c

3

4

5

5

12

13

7

24

25

8

15

17

9

40

41

These triples often appear in geometry problems, engineering tasks, and design measurements.

Applications of the Pythagoras Theorem

The theorem’s simplicity hides its broad utility. Here are just a few of its real-world applications:

1. Architecture and Construction

Engineers use it to calculate diagonal supports, slopes, or roof pitches to ensure structural integrity.

2. Navigation and Mapping

Pilots and sailors use the Pythagoras theorem to find the shortest route (the straight-line distance) between two points on a flat surface.

3. Computer Graphics

Graphic designers and game developers use it to determine distances between pixels or objects in 2D and 3D spaces.

4. Physics and Engineering

It helps calculate resultant vectors, forces, and distances in mechanics and kinematics.

5. Everyday Problem Solving

From measuring a television screen’s diagonal to figuring out a ramp’s length, the theorem appears in daily calculations.

Why Use Digital Calculator’s Pythagoras Theorem Calculator

At Digital Calculator, accuracy and simplicity are our top priorities. Here’s what sets our tool apart:

  • Instant Accuracy: Calculates precise results in real time.
  • User-Friendly Interface: Designed for quick input and easy understanding 
  • Educational Value: Perfect for students, teachers, and professionals. 
  • No Sign-Up Required: Free to use, anytime. 
  • Device Compatibility: Works seamlessly on desktops, tablets, and smartphones. 

Whether you’re verifying homework, solving geometric problems, or conducting technical measurements, this calculator is your reliable companion.

Tips for Using the Calculator Effectively

  • Always ensure that the triangle is right-angled before applying the theorem.
  • Keep units consistent (e.g., all in meters, centimeters, or inches).
  • Use decimal precision for measurements that aren’t whole numbers.
  • Recheck your inputs before calculating for the best accuracy.

Try It Now Accuracy Made Simple

Don’t waste time doing manual square and square-root operations.

Try our Pythagoras Theorem Calculator on Digital Calculator and get your results instantly. Whether you’re solving homework, designing a project, or exploring geometry, we help you calculate smarter, not harder.Explore more tools on Digital Calculator to simplify all your mathematical and scientific calculations from area, volume, and trigonometry to finance and conversions.

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Published: 10/10/2025