Right Triangle Calculator Calculators
Pythagoras, angles, area and perimeter from any two sides.
Right Triangle Calculator is a free online tool that pythagoras, angles, area and perimeter from any two sides. It runs entirely in your web browser using plain JavaScript, so files are processed on your own device and never uploaded to a server. There is no sign-up, no file size limit imposed by the site, no watermark and no paid tier.
- Price
- Free — no account, no quota, no watermark
- Category
- Calculators
- Where it runs
- In your browser, on your device
- Files uploaded
- None
- Technology
- plain JavaScript
- Settings
- 3
- Works offline
- Yes, after the first visit
About Right Triangle Calculator
This solves right triangles using Pythagoras, a² + b² = c², plus inverse sine for the angles. Leave any one side as zero and it solves for that one. Note that the hypotenuse must be the longest side — if you enter a hypotenuse shorter than a leg, no such triangle exists and the tool says so rather than returning nonsense.
How to use it
- Enter side a, side b and hypotenuse c.
- Results update the moment anything changes.
The 3 settings
| Setting | What it does | Default |
|---|---|---|
| Side a | A numeric value. | 3 |
| Side b | A numeric value. | 4 |
| Hypotenuse c | Leave 0 to solve for it. | 0 |
Under the hood
| Runs on | plain JavaScript — runs the whole thing |
| Controls | Side a, Side b, Hypotenuse c |
Questions
Does this work for non-right triangles?
No. Triangles without a right angle need the law of sines or cosines, which requires a different combination of inputs — typically two sides and the angle between them.
Is the arithmetic exact?
It uses double-precision floating point — about 15 significant figures, far more than the inputs justify. Displayed rounding is cosmetic; the underlying numbers are not rounded between steps, so chained results do not drift.