A free Pythagorean theorem calculator that finds the missing side, the angles and the area, drawn to scale.
Find the missing side of a right triangle, with its angles, area and a drawing to scale.
Your numbers
Fill in any 2 sides of a right triangle. c is the longest side, opposite the right angle.
Your result
Fill in the fields above to see your result.
Embed this tool on your site
Paste the code into any page: WordPress, Webflow, Squarespace, Ghost or plain HTML. It's free with the credit under it, which links back to navid.me.
This free Pythagorean theorem calculator finds the missing side of a right triangle from the other 2, with its angles, area and perimeter, and draws it to scale.
It works whichever 2 sides you know, the 2 legs or a leg and the hypotenuse.
I built it because the theorem is easy to remember and easy to apply backwards by mistake, adding when you should take away.
Here's the theorem, a worked example, and the mistake to watch for.
TL;DRKey takeaways
What is a Pythagorean theorem calculator?
A Pythagorean theorem calculator finds the third side of a right triangle from the other 2.
Builders use it to square a corner, and students to check geometry homework.
How the theorem works
The squares on the 2 short sides add up to the square on the long side.
A worked example
Here's the example the calculator loads: sides 3 and 4.
c = √(3² + 4²) = √(9 + 16) = √25 = 5. The angles are 36.87° and 53.13°, the area 6 and the perimeter 12.
Mistakes to avoid
These are the slips that come up most.
- Adding the squares when you know the hypotenuse: take away instead
- Forgetting the square root at the end
- Using it on a triangle without a right angle
Who is the Pythagorean theorem calculator for?
It's for students, builders and anyone measuring a diagonal, and these tools help around it.
- Scientific calculator – for any expression
- Fraction calculator – for answers as fractions
- Statistics calculator – for a list of numbers
Know 2 sides, and the third is always 1 square root away.
Plan your money with your AI
Take your numbers further in
Pythagorean Theorem Calculator FAQs
Questions about the pythagorean theorem calculator? Here's what to know.
A Pythagorean theorem calculator finds the missing side of a right triangle from the other 2.
In a right triangle, a² + b² = c², where c is the hypotenuse.
Square the 2 legs, add them and take the square root.
Square the hypotenuse, take away the square of the other leg, and take the square root.
A Pythagorean triple is 3 whole numbers that fit a² + b² = c², like 3, 4 and 5.
No, only for a triangle with a right angle.
About 36.87° and 53.13°, plus the right angle.
Yes, it's free with no sign-up.
It runs in your browser, and your numbers stay on your device.
I did.
I'm Navid Moazzez, and I made the Pythagorean theorem calculator as one of my free tools on navid.me.
More about me.
Navid Moazzez
AI business strategist & AI OS builder
Navid Moazzez helps creators and founders master AI and build their own AI Operating System (AI OS) to automate their business and life.
Navid.me is reader-supported. When you buy through links on this site, I may earn an affiliate commission. Learn more.
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