How To: Finding Difficult Miter Angles

by luke on June 25, 2011

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Cutting Miters, Bisecting Miters, Finding Miters, Angles

Working with Miters


An accurate miter joint provides beauty as well as strength. When working with stain-grade materials or large, detailed trim, there is no room for open miters or misaligned trim profiles. Although there are a number of “angle finders” on the market, it is often faster and more accurate to take a trip back to grade school math…

The Perfect Miter

To achieve the “perfect” miter, we will need a bevel square and a scribe or compass.

  • We begin setting our bevel square to the overall angle….

Perfect Miters, Cutting Miters

  • Transfer the angle onto a scrap piece of material. My personal favorite is a roughly 16″  piece of  plywood, 1×6 or  1×8 .

Cutting Miters, Miters, Perfect Miters

  • Set your scribe/compass to a reasonable arc for the size of your material. Note: A larger arc increases accuracy.
  • Mark equal distances from the point of intersection, (A), creating two new points: B, C

Cutting Miters

  • Mark equal and intersecting arcs from points B and C.

Cutting Miters

  • Use a straightedge to mark the angle intersecting “A” and “D”. The resulting angle is the perfect miter angle.

Cutting Miters, Miters, Bisecting Angles

  • Transfer this angle to your bevel square or simply set your saw to cut the bisect.


If you are still having trouble understanding how to bisect an angle, find the nearest twelve year old…he may know…

Good Luck


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