All tools · 📊 Math
📐 Triangle Calculator
Enter any 3 known parts of a triangle (sides and/or angles). We solve the remaining parts using the law of sines, law of cosines, or Pythagoras. Also computes area, perimeter, and triangle type.
Examples
SSS: 3, 4, 5Angles 36.87°, 53.13°, 90° · Area 6 · Right + Scaleneb=5, A=60°, c=7a ~ 6.24 · Area ~ 15.16B=45°, a=10, C=60°b ~ 8.16 · c ~ 9.66Frequently asked questions
What are SSS, SAS, ASA?
Combinations of known parts. SSS = three sides; SAS = two sides + included angle; ASA = two angles + included side. Each uniquely determines a triangle (up to reflection).
When does Pythagoras apply?
Only right triangles: a² + b² = c² where c is the hypotenuse. For non-right triangles use the law of cosines: c² = a² + b² − 2ab·cos(C).
Why might my triangle be "impossible"?
The triangle inequality: any one side must be less than the sum of the other two. If you enter 1, 1, 10 — there is no such triangle.
About this tool
Triangle Calculator runs entirely in your browser using standard Web APIs. No data is sent to any server. The source for this tool is in our public GitHub repository.
Related tools
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- 📊 Statistics Calculator — Mean, median, mode, standard deviation, variance, range from a number list.
Why this tool
vs typical free web-tool sites
| 1vw | Typical free site | |
|---|---|---|
| Price | Free | Free |
| Signup required | No | Often (for premium features) |
| Ads inside the tool | No | Yes (banner + video) |
| Data sent to server | No (browser-only) | Yes (inputs analyzed for ads) |
| Total tools | 96 | Often <20 or scattered across sites |
| Bookmarkable URL per tool | Yes | Mixed |
| Loads in under 1s | Yes (static) | Often slow (ad tracking) |
| Multilingual | EN / ES / PT / FR / DE | Usually EN only |
| Open source | Yes | No |