Notes: For a standard 90-degree corner, the miter cut angle is 45 degrees.
Miter Angle Calculator — Miter Cuts for Any Corner
A miter joint is the most common joint in finishing carpentry. While 90° corners need a 45° miter, real walls are rarely perfectly square. This calculator gives the exact miter angle for any corner.
Formula
Miter Angle = Corner Angle / 2
Common Angles
Corner
Miter Cut
Application
45°
22.5°
Octagonal frames
90°
45°
Standard corners
120°
60°
Hexagonal frames
135°
67.5°
Bay windows
Frequently Asked Questions
How do I calculate a miter angle?
Divide the corner angle by 2. For 90°: 45°. For 135°: 67.5°.
Miter angle for a bay window?
Most bay windows are 135° (67.5° miter) or 120° (60° miter). Always measure the actual angle.
Why do miter joints have gaps?
Usually the wall is not exactly the assumed angle. Use a digital angle finder and adjust your saw accordingly.
Stop Guessing. Start Building Smarter.
Built Simple gives you calculators, estimating tools, scheduling, and project management — all in one platform built for Australian builders.
