Gehrungswinkel-Rechner

How to use it: for a regular shape (a frame, planter or table with equal sides - like a square, hexagon or octagon), choose Regular shape and enter the number of sides. For an irregular corner - an out-of-square wall, an odd-shaped frame - choose Custom corner angle and enter the actual angle between the two pieces.

Formula. Every two-piece corner has an interior corner angle. The miter angle - the number you set on the saw, measured from a square (0°) cut - is half of what's left after the corner angle: miter angle = (180° − corner angle) / 2. For a regular polygon of n equal sides, the corner angle is (n − 2) × 180° / n, so the two modes agree: a 4-sided frame has a 90° corner and a 45° miter; a hexagon has a 120° corner and a 30° miter.

Worked example. With the default (regular shape, 4 sides): corner angle = (4−2) × 180 / 4 = 90°; miter angle = (180 − 90) / 2 = 45° - the familiar 45° setting for a square picture frame. For an 8-sided shape: corner angle = (8−2) × 180 / 8 = 135°; miter angle = (180 − 135) / 2 = 22.5°.

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.

Corner type

Regular shape (equal sides)

Number of sides, or corner angle

4

Primary result: Miter angle: 45.00 deg.

• 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.

This calculates the miter angle for a flat, single-bevel corner joint only - it does not compute compound miter/bevel pairs for angled (non-vertical) material such as crown moulding run at a spring angle, which needs a second, tilt-plane angle as well.

"Regular shape" mode assumes every side is the same length and every corner is identical, which is true for a regular polygon but not for an arbitrary irregular frame - measure each corner separately with the custom-angle mode if your shape isn't regular.