📐 Miter Angle Calculator
Enter the number of sides in your frame to get the exact miter angle to cut — plus the full joint angle where two ends meet — so a square, hexagon, octagon, or any regular frame closes cleanly.
🪚 Frame Miter Angles
What is a Miter Angle Calculator?
To build a regular, flat multi-sided frame from equal pieces, each end is mitered so the joints meet at the frame's interior angle. The per-cut miter is simply 180 divided by the number of sides — 45 degrees for a square frame, 30 for a hexagon, 22.5 for an octagon.
This tool gives you that cut angle instantly for any number of sides, along with the full joint angle. Because small errors compound around a closed frame, cut test pieces first and check the fit before you commit your project stock.
❓ Frequently Asked Questions
What miter angle do I cut for a picture frame?
A square, four-sided frame uses a 45-degree miter on each end, so the two mitered ends meet at a 90-degree corner. The general rule for a regular flat frame is 180 divided by the number of sides — 45 degrees for four sides.
What angle is a hexagon or an octagon?
A six-sided (hexagonal) frame is mitered at 30 degrees per end (180 ÷ 6), and an eight-sided (octagonal) frame at 22.5 degrees (180 ÷ 8). The calculator returns both the per-cut miter angle and the full joint angle for any number of sides you enter.
Do I set my miter gauge to the miter angle or the joint angle?
You set the per-cut miter angle. On most saws the gauge or blade is referenced from square (90 degrees), so a 45-degree picture-frame cut is what you dial in. The full joint angle (twice the miter) is just the total where the two ends come together.
Why won't my mitered frame close up tightly?
Tiny errors add up around a closed frame, so a fraction of a degree off shows as a gap. Cut matched pairs, sneak up on the fit with test pieces, make sure your stock is a consistent width, and check the gauge against a known-square reference before committing to your final pieces.