What mitre angle do I need for a hexagonal planter?

A regular hexagon (6 sides) has an interior angle of 120 degrees. The mitre angle for each joint is 30 degrees. Set your mitre saw to 30 degrees from perpendicular to cut each end of the six segments.

How do I calculate angles for an octagonal frame?

An octagon has 8 sides with interior angles of 135 degrees. The mitre angle is 22.5 degrees. This is a common setting on most mitre saws. Each segment needs a 22.5 degree cut on both ends.

Should I account for saw kerf in polygon builds?

Yes. Each mitre cut removes material equal to the saw kerf (typically 2-3mm). For a hexagon with 12 cuts, this can add up to 24-36mm of total material loss. Add kerf allowance to each segment length when cutting.

What is the difference between mitre angle and bevel angle?

For a flat polygon (all pieces lying in the same plane), the mitre and bevel angles are the same. The mitre is the angle cut across the face of the board, while the bevel is the angle cut across the edge. For 3D polygonal shapes (like bowls), these angles differ.

WoodCalcs

Polygon Angle Calculator — Mitre Angles for Polygonal Builds

Calculate interior angles, mitre angles, and diameters for polygonal woodworking projects like planter boxes and frames.

Number of Sides

3 (triangle) to 24 sides

Segment Length

Length of each side piece

Material Thickness

Thickness of the stock material

How We Calculate This

This calculator determines the cutting angles and dimensions for regular polygons used in woodworking.

Angle formulas

Interior angle = (n - 2) x 180 / n

Mitre angle = (180 - Interior angle) / 2

Diameter formulas

Circumscribed diameter = Segment length / sin(180/n)

Inscribed diameter = Segment length / tan(180/n)

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Always verify measurements and material quantities before cutting or purchasing.