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Hypotenuse Calculator (Pythagorean Theorem)
Quick answer
If side a is 3 and side b is 4, the hypotenuse is 5.
Pythagorean theorem: c = √(a² + b²).
Enter your values
Hypotenuse
5
The longest side of the right triangle, opposite the right angle.
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About the Hypotenuse Calculator (Pythagorean Theorem)
In a right-angled triangle, the hypotenuse is the longest side, opposite the right angle. The Pythagorean theorem finds it from the other two sides. Enter both shorter sides.
The classic example: sides of 3 and 4 give a hypotenuse of 5.
Pythagorean theorem
c = √(a² + b²)
Things to keep in mind
- It only works for right-angled triangles.
- Use it to check that a corner is square, or to find a diagonal such as the length of a ladder or a TV screen.
- To find a shorter side instead, use the Pythagorean Missing Leg calculator.
See how the result changes
Each table re-runs this calculator with one value changed and everything else left as it is.
Hypotenuse by side a
If side a goes from 3 to 4.5, hypotenuse changes from 5 to 6.0208 (+20%).
| Side A | Hypotenuse |
|---|---|
| 1.5 | 4.272 |
| 2.25 | 4.5894 |
| 3start | 5 |
| 4.5 | 6.0208 |
| 6 | 7.2111 |
Hypotenuse by side b
If side b goes from 4 to 6, hypotenuse changes from 5 to 6.7082 (+34%).
| Side B | Hypotenuse |
|---|---|
| 2 | 3.6056 |
| 3 | 4.2426 |
| 4start | 5 |
| 6 | 6.7082 |
| 8 | 8.544 |
MATH GUIDE
A quick guide to Right Triangle Hypotenuse
Use it to get an accurate hypotenuse in seconds — free, with no sign-up.
Instant results
See your hypotenuse the moment you enter your numbers.
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Every calculator here is free to use, with no account required.
Accurate & transparent
The same standard formula runs on our server for every calculation.
How to Use the Right Triangle Hypotenuse Calculator
1
Enter Side A
Provide your side a.
2
Enter Side B
Provide your side b.
3
View Your Results
Get your hypotenuse instantly, calculated on our server.
What is Right Triangle Hypotenuse?
This math tool works out your hypotenuse instantly, so you don't have to do the math by hand.
“One quick calculation, so you always know your hypotenuse before you decide.”
What Affects Your Hypotenuse
Your hypotenuse depends on the values below.
Side A
Changing your side a changes your hypotenuse.
Side B
Changing your side b changes your hypotenuse.
Example Result
Here's what you can expect from a right triangle hypotenuse calculation:
- Side A
- 3
- Side B
- 4
- Hypotenuse
- 5
Frequently Asked Questions
- How does side a affect hypotenuse?
- If side a goes from 3 to 4.5, hypotenuse changes from 5 to 6.0208 (+20%).
- How does side b affect hypotenuse?
- If side b goes from 4 to 6, hypotenuse changes from 5 to 6.7082 (+34%).
- How to calculate right triangle hypotenuse?
- Fill in side a and side b in the Hypotenuse Calculator (Pythagorean Theorem) above and your hypotenuse is calculated instantly. Change any value to see how the result responds.
- What does an example right triangle hypotenuse calculation look like?
- If side a is 3 and side b is 4, the hypotenuse is 5.
- Is this calculator free to use?
- Yes — every calculator on this site is completely free, with no sign-up or account required.
- How accurate is this calculator?
- It uses the standard formula and calculates on our server for every request, so results are precise for the values you enter.
- Is my data saved anywhere?
- No. Nothing you enter is stored or sent anywhere unless you choose to share a link with your values included.
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