Miter Angle Calculator
Use this miter angle calculator to estimate the cut angle needed for a corner joint or framed layout. It is useful for picture frames, trim, and other joinery where two pieces meet at an angle. Enter the board widths and corner angle to get a practical cut angle for your saw or layout marks.
Result
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What This Miter Angle Calculator Helps You Do
Use this miter angle calculator to estimate the cut angle needed for a corner joint or framed layout. It is useful for picture frames, trim, and other joinery where two pieces meet at an angle. Enter the board widths and corner angle to get a practical cut angle for your saw or layout marks.
How to Calculate Miter Angle Calculator
- Choose the layout - Pick the mode that matches your joinery: simple corner, width ratio, or custom angle.
- Enter the angles and widths - Add the corner angle and any board widths needed for the selected layout.
- Check the saw setting - Use the calculated angle as the saw or layout angle before you make the cut.
- Verify the fit - Dry-fit the pieces before final fastening so you can catch any angle mismatch early.
Miter Angle Calculator Formula
| Symbol | Definition | Unit |
|---|---|---|
| θ | Corner angle | deg |
| α | Miter angle | deg |
| w1 | Board width A | m |
| w2 | Board width B | m |
Worked Examples
- cornerAngle: 90
Result: Miter angle = 45.00 deg
A classic right-angle corner uses a 45 degree miter on each piece. The estimate is 45.00 deg.
- boardWidthA: 0.12
- boardWidthB: 0.08
Result: Miter angle = 56.31 deg
When trim widths differ, the angle shifts and should be checked before cutting. The estimate is 56.31 deg.
- boardWidthA: 0.11
- boardWidthB: 0.09
- cornerAngle: 100
Result: Miter angle = 0.01 deg
A custom corner angle helps when you are trimming an irregular frame or assembly. The estimate is 0.01 deg.
- cornerAngle: 120
Result: Miter angle = 60.00 deg
For an obtuse corner, the miter angle simply tracks the corner angle half-way point. The estimate is 60.00 deg.
How to Interpret Your Results
| Range | Meaning | Action |
|---|---|---|
| < 30 deg | Sharp cut | Use extra care when setting the saw and clamping the work. |
| 30–45 deg | Common trim cut | Typical for picture frames and many interior corners. |
| 45–60 deg | Broad corner | Check the fit with a test cut before final assembly. |
| > 60 deg | Wide angle | Verify the layout carefully because the joint is less forgiving. |
Frequently Asked Questions
Sources
Last reviewed: March 2026