Calculator Inputs
Example Data Table
| Rise | Run | Ratio (rise/run) | Bevel Angle (deg) | Percent Slope | Pitch (rise per 12) |
|---|---|---|---|---|---|
| 3 | 12 | 0.2500 | 14.0362 | 25.000% | 3.000 / 12 |
| 6 | 12 | 0.5000 | 26.5651 | 50.000% | 6.000 / 12 |
| 9 | 12 | 0.7500 | 36.8699 | 75.000% | 9.000 / 12 |
| 12 | 12 | 1.0000 | 45.0000 | 100.000% | 12.000 / 12 |
Values are shown for quick verification and training.
Formula Used
The calculator treats the slope as a right triangle where:
- Rise is the vertical change.
- Run is the horizontal distance.
- Bevel Angle is the angle from the run to the slope.
Main relationship
Angle (degrees) = arctan(Rise ÷ Run) × (180 ÷ π)
Derived values
- Ratio = Rise ÷ Run
- Percent Slope = Ratio × 100
- Pitch (rise per 12) = Ratio × 12
- Length per 1 run = √(1 + Ratio²)
How to Use This Calculator
- Select the calculation mode that matches your available measurements.
- Enter rise and run, or enter pitch, percent slope, or angle.
- Press Calculate to show results above the form.
- Use the bevel angle as your saw setting for the cut.
- Download CSV or PDF to save the job record and share.
Professional Notes
1) Why bevel angles matter on site
Bevel settings control how tightly two sloped faces meet. Accurate angles reduce gaps, minimize filler, and protect finishes. This calculator converts common field measurements into a reliable bevel angle, so you can set a saw, plane, or grinder with confidence.
2) Inputs that match real measurements
Jobs rarely start with a known angle. More often you have rise and run from a level and tape, a roof pitch like 6/12, or a grade percentage from plans. Each input mode is translated into the same slope ratio (rise/run) for consistent results.
3) Core math in one sentence
The bevel angle is computed as arctan(rise ÷ run) in degrees. The complement is 90° minus that angle, which helps when checking a square reference or verifying a layout line.
4) Typical construction data points
A 3/12 pitch is about 14.04°, 6/12 is about 26.57°, and 12/12 is 45°. An 8% grade corresponds to a ratio of 0.08 and an angle near 4.57°. These benchmarks are useful for quick sanity checks before cutting.
5) Using ratio, percent, and pitch together
Because the ratio is the common language, you can move between formats: percent = ratio × 100 and pitch per 12 = ratio × 12. This helps when the plan set uses percent grade, but your crew communicates in pitch.
6) Applying the angle to tools
Use the bevel angle as the tool setting when cutting along the slope direction. For repeatable work, cut a test piece, dry-fit, then lock the bevel stop. If the material is thick or irregular, small adjustments may be needed due to blade kerf and deflection.
7) Accuracy and tolerances
Small input errors can shift the angle, especially on shallow slopes. Measure run as long as practical, keep the level fully supported, and record values to at least one decimal. On finish carpentry, a 0.5° error can create visible gaps on miters and trims.
8) Documentation for crews and clients
Exporting CSV or PDF keeps a clean record of the measurement method, bevel setting, and derived values. This is helpful for punch lists, repeat work, and coordinating between framing, roofing, and finish trades. Consistent records reduce rework and improve jobsite communication.
FAQs
1) What is the bevel angle in this calculator?
The bevel angle is the slope angle measured from the horizontal run to the sloped edge. It is calculated from your inputs and can be used as a saw or grinder bevel setting.
2) When should I use the complement angle?
Use the complement when you are referencing a square or a vertical line. It helps confirm layout geometry because the bevel angle and complement always sum to 90 degrees.
3) How do I enter roof pitch like 6/12?
Select the pitch mode and enter the rise number (for 6/12, enter 6). The calculator assumes a run of 12 and returns the bevel angle and related slope formats.
4) What does “percent slope” mean?
Percent slope is rise divided by run, multiplied by 100. For example, 8% means 8 units of rise for every 100 units of run, which is common in grading and ramps.
5) Why do I see “length per 1 run”?
This value is the hypotenuse length when the run equals 1 unit. It is useful for scaling, estimating diagonal lengths, and checking whether a slope line matches measured dimensions.
6) Can I mix units for rise and run?
Avoid mixing units. Rise and run must be in the same unit so the ratio stays correct. The unit selector is for labeling and documentation, not for automatic unit conversion.
7) Why does my real-world fit differ slightly from the output?
Material movement, tool calibration, blade kerf, and measurement error can shift results. Cut a test piece, verify the fit, and adjust in small increments when finish quality is critical.