Construction

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Angle Cut Calculator.

Find the equal-piece miter angle for an included corner angle.

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Set your values

Results update as you type.

Results use only the stated formula and entered units; they are not building-code, equipment-sizing, or structural design advice.

Use Cases

Cutting trim for non-standard corners

When installing crown molding or baseboards on walls that meet at unusual angles, use this calculator to find the exact miter angle for each piece.

Example: For a 135-degree corner, enter 135 to get a 67.5-degree miter angle.

Building picture frames or boxes

When constructing frames or boxes with equal sides, determine the miter angle for each corner to ensure a perfect fit.

Example: For a hexagonal frame (120-degree corners), enter 120 to get a 60-degree miter angle.

Frequently Asked Questions

What is an included corner angle?
The included corner angle is the total angle formed at the corner where two surfaces meet. For example, a standard 90-degree corner has an included angle of 90 degrees. This calculator uses that angle to determine the miter angle for each piece.
How is the miter angle calculated?
The miter angle is calculated by dividing the included corner angle by the number of pieces (assumed to be two for a standard corner). For a 90-degree corner, each piece is cut at 45 degrees. The calculator does this division for you.
Can I use this for corners other than 90 degrees?
Yes, you can input any included corner angle in degrees. For example, a 120-degree corner would require a 60-degree miter angle on each piece. This calculator works for any angle you enter.

Tips & Common Mistakes

Tips

  • Always measure the included corner angle accurately using a protractor or angle finder for precise results.
  • Double-check your saw's miter gauge calibration before making cuts, as even slight errors can affect the fit.
  • For pieces longer than the saw's capacity, consider using a stop block to ensure consistent cuts.
  • Test your miter angle on scrap wood first to verify the fit before cutting your final pieces.

Common Mistakes to Avoid

  • Forgetting to divide the included angle by two when cutting two pieces for a corner.
  • Using the outside angle instead of the included angle, which can lead to incorrect miter settings.
  • Assuming all corners are 90 degrees without measuring, especially in older homes or custom builds.

Last updated: August 13, 2026