Miter Saw Angle Calculator

Cutting precise angles is one of the biggest challenges in woodworking, trim work, and DIY home projects. A small mistake in your measurements can leave gaps, uneven joints, or wasted material. That’s where our Miter Saw Angle Calculator comes in. We developed this free online tool so anyone can quickly find the right miter and bevel angles for crown molding, frames, or tricky corner cuts.

With simple inputs like your corner angle and spring angle, the calculator shows you exact saw settings. No more guessing, no more trial and error just clean, professional cuts every time.

How to Calculate Mitre Cut Angle

When working with a miter saw, the most important thing to understand is how to split your corner angle.

• The corner angle (C) is the angle of the wall or frame (for example, 90° in a square corner).
• The wall half-angle (W) is simply C ÷ 2.
• The spring angle (S) applies when cutting crown molding. This is the tilt of the molding against the wall (usually 38° or 45°).

The formulas used in our calculator are based on trigonometry:

Miter angle = arctan(sin(S) ÷ tan(W))

Bevel angle = arcsin(cos(S) × cos(W))

For simple flat cuts like picture frames:

Simple miter = 90° − W

These formulas give the most accurate results possible, and the calculator does all the math instantly.

What is the 31.6 Degree on a Miter Saw?

If you’ve looked at your miter saw scale, you may have noticed a special marking at 31.6°. This is a factory preset for crown molding with a 38° spring angle inside a 90° corner. It is one of the most common cuts in trim carpentry.

Using the formula:

Miter = arctan(sin(38°) ÷ tan(45°)) ≈ 31.6°

Bevel = arcsin(cos(38°) × cos(45°)) ≈ 33.9°

That’s why most saws mark 31.6° and 33.9° - so you can quickly cut crown molding without needing to measure every time.

What is the Miter Angle for a 135 Degree Angle?

Sometimes you’ll work with walls that aren’t square. A 135° angle is common in bay windows or angled walls.

To find the miter setting:

Wall half-angle W = 135° ÷ 2 = 67.5°

Simple miter = 90° − 67.5° = 22.5°

So, for a 135° inside corner without beveling, you set your saw at 22.5°. The calculator gives you this instantly when you enter the numbers.

How to Set Miter Saw for 45 Degree Cuts

A 45° cut is the most common setting for picture frames, door trim, and window casings. If your corner angle is 90°, the wall half-angle is 45°. That means:

Simple miter = 90° − 45° = 45°

To make a perfect square frame:

• Set your miter saw to 45°
• Make opposite cuts for each pair of sides
• Join them to form 90° corners

The calculator confirms this with step-by-step results so beginners can learn while cutting.

How to Use the Miter Saw Angle Calculator

1. Enter the corner angle of your wall or frame (in degrees).
2. Enter the spring angle if cutting crown molding (38° or 45° are common).
3. Select whether you want to use the primary or alternate formula set (the primary works for most cases).
4. Click calculate.
5. The tool shows you:
   - Wall half-angle
   - Exact miter angle
   - Exact bevel angle
   - Simple miter (for flat cuts)

You can also view step-by-step calculations to understand the math behind it.

Final Verdict

Whether you’re a professional carpenter or a DIY homeowner, the Miter Saw Angle Calculator makes cutting accurate joints effortless. From standard 90° corners to unusual angles like 135°, it takes out the guesswork and helps you save time, money, and material.

No matter if you’re building frames, installing crown molding, or finishing trim, our calculator ensures your cuts are always clean and precise.

FAQs

How do I calculate mitre cut angle without a calculator?

Divide the corner angle by 2 and subtract from 90°. For crown molding, you’ll also need to apply trigonometric formulas, which is why the calculator is handy.

What is the 31.6° on my miter saw used for?

It’s a preset for cutting 38° crown molding in a 90° corner.

What angle do I cut for a 135° corner?

You set your saw to 22.5°.

How do I cut a 45° angle?

For a 90° corner, set the saw at 45° and make opposite cuts for both pieces.

Does this calculator work for all saw brands?

Yes, the math is universal. It applies to any miter saw brand or model.