Free tool · Cutting & sheet goods
Miter Angle Calculator
Get the miter angle for any corner from its angle, or for a multi-sided frame from its number of sides. Each piece is cut at half the joint.
Regular frame reference
| Sides | Corner angle | Saw setting |
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Set your saw to the miter setting, and cut both mating pieces at that angle. A butt joint and a mitered joint share the same miter setting, the miter just adds a bevel for compound (sloped) work.
Miter Angle Calculator, explained
How do you calculate a miter angle?
Two pieces meeting at a corner each get cut at half the turn. For a square 90 degree corner that is a 45 degree miter on each piece. For any corner angle, the miter on each piece is (180 - corner angle) / 2. So a 135 degree corner takes a 22.5 degree miter, and a sharp 60 degree corner takes a 60 degree miter.
For a closed frame with equal sides, the miter on each end is simply 180 divided by the number of sides. A four-sided frame is 45 degrees, a six-sided (hexagon) frame is 30 degrees, and an eight-sided (octagon) frame is 22.5 degrees. This calculator does both: enter a corner angle, or enter the number of sides.
How it works
How the Miter Angle Calculator works.
By corner: Miter = (180 - corner angle) / 2 | By frame: Miter = 180 / number of sides - Choose how you are working: from a single corner angle, or from the number of sides in a frame.
- For a corner, enter the corner angle (90 for a square corner). For a frame, enter the number of equal sides.
- Read the miter angle to set on your saw for each piece.
- Cut both mating pieces at that angle so the joint closes cleanly.
Example: a square picture frame has 4 sides, so each end is mitered at 180 / 4 = 45 degrees. A hexagon planter has 6 sides, so each end is 180 / 6 = 30 degrees.
Miter Angle Calculator FAQ
Miter Angle Calculatorquestions.
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What miter angle is a 90 degree corner?
45 degrees on each piece. Two 45 degree miters meet to close a 90 degree corner. The rule is miter = (180 - corner) / 2, so (180 - 90) / 2 = 45.
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What is the miter angle for a hexagon?
30 degrees. A hexagon has 6 sides, and the miter for a regular frame is 180 divided by the number of sides, so 180 / 6 = 30 degrees on each end.
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How do I miter an odd-angled corner?
Measure the corner angle with a bevel gauge or angle finder, then cut each piece at (180 - corner angle) / 2. For example a 100 degree corner needs a 40 degree miter on each piece.
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How do you calculate mitered corners?
To miter a corner, divide the corner angle by two. A standard 90-degree corner splits into two 45-degree cuts, so each piece is cut at 45 degrees. For other corners, take the joint angle, divide by two, and set your saw to that figure. Enter the corner angle in the calculator above and it returns the exact per-piece miter setting instantly.
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What is the miter angle formula?
The basic formula is miter angle equals the corner angle divided by two. For a four-sided box meeting at 90 degrees, that is 45 degrees per cut. For a hexagon, the corner is 120 degrees, giving 60-degree pieces, though saws are often set to the complementary 30. The calculator does this math for you, including the saw-scale conversion.
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What is a miter angle used for in woodworking?
A miter angle joins two pieces at an angle without exposing the end grain, common in face frames, crown molding, picture frames, and decorative cabinet trim. Cutting both mating pieces at half the corner angle produces a clean, seamless joint. Accurate miters matter most on visible cabinetry edges where a gap would be obvious.
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How do you find a miter angle with a speed square?
Hold the speed square against the workpiece edge and pivot it from the pivot point until the desired degree mark lines up with the edge. The degree scale along the hypotenuse reads the angle directly, which you then transfer with a pencil line. For repeatable cuts, set that same reading on your miter saw scale.
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What is the difference between a miter angle and a bevel angle?
A miter angle is the horizontal cut across the face of the board, set by swinging the saw left or right. A bevel angle is the vertical tilt of the blade, cutting through the thickness. A compound cut combines both at once, which is common on crown molding. The calculator handles single miters and compound setups separately.
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