Miter Angle For a 5 Sided Box

A regular 5-sided box needs a 36° miter at each end — not the 40° or 45° a quick mental guess tends to land on, which is exactly why this is the single most commonly mis-guessed angle in the common polygon set.

Why this one specifically

Five sides is odd in both senses of the word: it's the first side count in the common sequence where the "nice," easily-estimated angles of 4, 6, 8, 10 and 12 sides stop applying, and pentagonal boxes and planters are common enough in practice that people reach for this exact angle regularly, then second-guess themselves when the saw's degree scale doesn't show an obvious round number.

What moves the number

Nothing about material or project type changes this figure — it's pure geometry, fixed entirely by the 5-sided count. 36° is at least a whole-number angle, unlike the 7-sided case one step further into the odd counts, so a standard miter saw's whole-degree markings can hit it exactly without needing a digital angle gauge.

See the miter angles for common polygons explainer for the full table and derivation, compare against the 4-sided and 6-sided neighbours, and confirm the exact figure in the angle calculator.