Right Triangle Calculator

Enter any two known values — two sides, or one side and one angle — and get everything else: both legs, the hypotenuse, both non-right angles, and the area.

One of the two sides forming the right angle — leave blank if unknown.
The other side forming the right angle — leave blank if unknown.
The side opposite the right angle, the triangle's longest side — leave blank if unknown.
The angle directly across from Leg A, not the one adjacent to it.

Fill in any two, leave the rest blank

A right triangle only needs two known values (beyond the 90° angle itself) to be fully determined — two sides, or one side plus one of the non-right angles. Enter whichever two you actually have and leave the other two fields empty; the calculator figures out which case applies and solves the rest with the Pythagorean theorem and the standard sine/cosine/tangent relationships.

Where this comes up on the floor

Dovetail measurements over pins, angled bracket layouts, tapers expressed as rise-over-run, and checking a sine bar setup against a print's angle callout are all, underneath, just solving a right triangle — this saves re-deriving the same handful of relationships by hand every time one comes up.

Angle A is always opposite Leg A

Keep the convention consistent: the angle you enter or receive back for "Angle A" is always the one directly across from Leg A, not adjacent to it — getting legs and angles crossed is the single most common way to introduce an error into an otherwise correct triangle calculation.

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