Understanding Miter Angles
A miter joint is formed when two pieces are cut at angles so their cut edges meet to create a corner. For two equal pieces, each miter cut is half of the desired corner angle. A 90° corner, for example, requires two equal 45° miter cuts.
Miter cuts are commonly used for picture frames, trim, molding, woodworking, cabinetry, and other projects where two pieces need to meet cleanly at a corner.
Corner Angle vs. Miter Cut
The angle of the finished corner and the angle cut on each piece are not the same measurement. If two pieces contribute equally to the joint, the required cut angle on each piece is one-half of the finished corner angle.
For example, a 60° corner requires two 30° cuts, while a 120° corner requires two 60° cuts.
Angles Between Two Lines
When two lines meet or cross, there can be more than one way to describe the angle between them. The smaller angle can be acute, right, obtuse, or straight, while the angle traveling the longer way around the point is a reflex angle.
This can be useful for checking layouts, comparing directions, planning cuts, or working with lines that do not meet at a standard 90° corner.
Measuring Before You Cut
Real-world corners are not always perfectly square. Walls, trim, framing, and existing structures can be slightly out of alignment, so measuring the actual corner angle can produce a better fit than simply assuming it is 90°.
When making a final cut, also check how your particular saw displays angles. Some saw scales reference the blade position from square rather than displaying the geometric angle in the same way you measured it.