Angle calculator

For two wall or line directions, subtract their common vertex from a point on each ray, then enter the X and Y components. The signed angle is positive counterclockwise in Cartesian coordinates. A triangle’s angles total 180°. A regular n-sided polygon has interior angle 180° − 360°/n and exterior turning angle 360°/n.

The result above uses these exact values. This snapshot is included when the page is printed so the output can be checked against the original measurements.

Angle model

Two rays from a common vertex

First ray X component

1

First ray Y component

0

Second ray X component

0

Second ray Y component

1

Primary result: Smaller angle: 90 °.

• Measure from the datum or reference edge described by this tool, and do not mix inside, outside and centerline dimensions.
• Keep inputs in the displayed units and preserve more precision than the final cutting or purchasing tolerance requires.
• When the result is close to a limit, verify it with a test piece, field measurement, manufacturer drawing or qualified project professional.

Each ray must have nonzero length. The diagram shows the angle magnitude with the first ray normalized to horizontal. Triangle inputs must be positive and sum to less than 180°. Regular-polygon results do not apply to irregular polygons; a wall measurement needs actual direction data.