Triangle CalculatorSolve any triangle
Examples
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Pinned, kept fixedCalculated
  • Drag a corner to reshape; angles snap to 15° (hold Alt to move freely)
  • Arrow keys move a focused corner
  • Click a value to type it: Enter applies, Esc cancels, ↑ ↓ nudge, Shift ×10
  • Drag a value sideways to adjust it
  • Click a pin to keep a value fixed
  • Drag a corner to reshape; angles snap to 15°
  • Tap a value to type it, − and + step it
  • Slide a value sideways to adjust it
  • Tap a pin to keep a value fixed
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About Triangle Calculator

Triangle Calculator solves triangles. Give it any three values, at least one of them a side, and it works out the rest: the remaining sides and angles, area, perimeter, heights, medians and the radii of the inscribed and circumscribed circles.

The diagram is the main tool. Drag a corner and every value follows. Tap a value to type a new one, and pin the values you want to keep fixed. Each result comes with the working, step by step, using the law of sines and the law of cosines, so you can follow and check every number.

Who it is for

Students checking homework, teachers preparing worksheets, and anyone who needs a triangle in practice: in a workshop, on a building site, in design or in code.

How it works

All calculations run in your browser. Your triangle is not sent to a server. The results can be copied or downloaded as text, tables, images and code for LaTeX, GeoGebra and CAD programs.

Triangle Calculator is free to use, with no ads and no account.

No warranty

Triangle Calculator is provided "as is", without warranty of any kind. Calculated values, diagrams and other outputs may be incorrect. Check results independently before you rely on them, especially for construction, safety-related or financial decisions.