Angle Cut Calculator

Learn how to find angle cuts for knee bracing purposes and alike using the angle cut calculator.

Miter angle35.2644°set the saw table to this

Bevel angle30°tilt the blade to this

Corner angle90°half angle 45°

Spring angle45°how far the moulding leans off the wall

Flat miter, for comparison45°what you would use if the moulding lay flat

Saw settings35.26° miter, 30° bevel

The two standard crowns45° spring: 35.26° / 30°52° spring: 31.62° / 33.86° — the pair marked on most mitre saws

The formula

miter = 180° ÷ n for an n-sided frame; bevel from the spring angle

Halve the corner

Two pieces meeting at a corner each take half of it, so a 90° corner needs two 45° cuts. For a regular polygon the corner angle is 180° − 360°/n, so each miter is 180°/n: 45° for a square, 30° for a hexagon, 22.5° for an octagon.

Compound miters are harder because the moulding leans off the wall. The cut then has to be right in two planes at once, which is why a crown moulding in an ordinary square corner needs 31.6° of miter and 33.9° of bevel rather than a simple 45°.

Whatever the arithmetic says, measure the actual corner. Very few walls are truly square, and a 2° error at the wall becomes a visible gap at the miter.