Inches Per Foot to Degrees Calculator
Convert slope from inches per foot to degrees instantly. Perfect for roofers, carpenters, civil engineers, and DIY builders.
Inches per foot describes rise over 12 inches of run. This calculator converts that slope measurement to angular degrees using trigonometry.
Inches/Foot to Degrees
Enter slope in inches per foot
Precision & Display
Calculation Results
Enter slope value
then click "Calculate" for results
How to Convert Inches Per Foot to Degrees
In construction and roofing, slope is often described as "inches per foot." For example, a 4-in-12 slope means the surface rises 4 inches for every 12 inches (1 foot) of horizontal run. Engineers and designers sometimes need the angle in degrees instead, which requires a bit of trigonometry.
The conversion uses the arctangent function. First, divide the rise by the run. Since one foot equals 12 inches, the formula becomes:
Example Calculation
Inches Per Foot to Degrees Reference Table
Here's a quick reference table showing common slope conversions:
| Inches/Foot | Slope Ratio | Percent | Degrees |
|---|---|---|---|
| 1 | 0.083 | 8.33% | 4.76° |
| 2 | 0.167 | 16.67% | 9.46° |
| 3 | 0.25 | 25.00% | 14.04° |
| 4 | 0.333 | 33.33% | 18.43° |
| 5 | 0.417 | 41.67% | 22.62° |
| 6 | 0.5 | 50.00% | 26.57° |
| 7 | 0.583 | 58.33% | 30.26° |
| 8 | 0.667 | 66.67% | 33.69° |
| 9 | 0.75 | 75.00% | 36.87° |
| 10 | 0.833 | 83.33% | 39.81° |
| 11 | 0.917 | 91.67% | 42.51° |
| 12 | 1.0 | 100.00% | 45.00° |
| 14 | 1.167 | 116.67% | 49.40° |
| 16 | 1.333 | 133.33% | 53.13° |
| 18 | 1.5 | 150.00% | 56.31° |
| 20 | 1.667 | 166.67% | 59.04° |
| 24 | 2.0 | 200.00% | 63.43° |
| 30 | 2.5 | 250.00% | 68.20° |
| 36 | 3.0 | 300.00% | 71.57° |
| 48 | 4.0 | 400.00% | 75.96° |
A 12-in-12 slope equals exactly 45 degrees because the rise equals the run. Steeper slopes have higher inch-per-foot values and approach 90 degrees as the ratio increases. For roof pitch, most residential roofs fall between 4/12 and 12/12.