Slope Calculator
A 2 ft rise and a 50 ft run is a 4.00 percent grade, 2.29 degrees, a 1:25.00 ratio, and 0.48 inches per foot.
Last updated . Rise and run start in feet. Percent grade is rise ÷ run × 100. The reverse run starts from a 4 percent slope and a 2 ft rise.
A slope calculator and grade calculator for rise and run. It also solves the run from a percent grade, an angle, a 1:x ratio, or inches per foot.
Roof pitch, x/12, and the roof-area multiplier: roof pitch calculator. A cut in the ground: excavation calculator.
Rise, run, and grade
Run from a slope and a rise
Percent grade is rise ÷ run × 100. The ratio is 1 unit of rise to x units of run. Inches per foot is the rise, in inches, for each foot of horizontal run. Roof pitch, with the run fixed at 12 and a roof-area multiplier, is a different page.
Results
How the grade is calculated
Percent grade = (rise ÷ run) × 100. Degrees = atan(rise ÷ run). The ratio 1:x uses x = run ÷ rise, so 2 ft of rise over 50 ft of run is 1:25.00. Inches per foot = (rise ÷ run) × 12, which is 0.48 for that same slope. The run is the horizontal distance, not the slope distance along the ground.
The reverse run is separate. Run = rise ÷ (percent ÷ 100). At 4 percent and a 2 ft rise, that is 2 ÷ 0.04 = 50.00 ft. Degrees use run = rise ÷ tan(degrees). A ratio uses run = rise × x. Inches per foot uses run in feet = rise in inches ÷ inches per foot.
Common grades
These rows use the same conversion. Set the rise and run, or the reverse slope, to read them on the tool.
| Grade | Degrees | Ratio | Inches per foot |
|---|---|---|---|
| 1% | 0.57° | 1:100.00 | 0.12 |
| 2% | 1.15° | 1:50.00 | 0.24 |
| 4% | 2.29° | 1:25.00 | 0.48 |
| 5% | 2.86° | 1:20.00 | 0.60 |
| 8.33% (1 in/ft) | 4.76° | 1:12.00 | 1.00 |
| 10% | 5.71° | 1:10.00 | 1.20 |
Worked example
Leave the rise at 2 ft and the run at 50 ft. Percent grade reads 4.00%. Degrees read 2.29°. Ratio reads 1:25.00. Inches per foot reads 0.48 in/ft. Leave the known rise at 2 ft and the slope at 4 percent. The run from that slope reads 50.00 ft · 15.24 m.
Slope questions
What is a 4 percent grade?
Leave the rise at 2 ft and the run at 50 ft. Percent grade reads 4.00%. Degrees read 2.29°. The ratio reads 1:25.00. Inches per foot reads 0.48 in/ft. Percent grade is (2 ÷ 50) × 100.
How many inches per foot is a 4 percent slope?
0.48 inches per foot. Inches per foot = (rise ÷ run) × 12, so 0.04 × 12 = 0.48. The same 2 ft rise and 50 ft run reads 0.48 in/ft on the inches line.
How do I find the run from a slope and a rise?
Leave the known rise at 2 ft, the slope type on percent grade, and the slope value at 4. The run line reads 50.00 ft · 15.24 m. Run = rise ÷ (percent ÷ 100) = 2 ÷ 0.04.
What if I type the rounded 2.29 degrees instead of 4 percent?
Set the slope type to degrees and type 2.29, with the known rise still at 2 ft. The run reads 50.01 ft · 15.24 m. The 0.01 ft is the rounding in 2.29 degrees. The exact angle of a 4 percent grade is atan(0.04), and 4 percent itself returns 50.00 ft.
What is a 1:12 slope?
Set the slope type to ratio and type 12, with the known rise at 1 ft. The run reads 12.00 ft · 3.66 m. A 1:12 slope is 8.33 percent, 4.76 degrees, and 1.00 inch per foot. Set the rise to 1 ft and the run to 12 ft to read those lines.
Can the rise and the run use different units?
Yes. Set the rise to 2 ft and the run to 600 in. 600 inches is 50 ft, so the grade still reads 4.00%, 2.29°, 1:25.00, and 0.48 in/ft. Each side has its own unit menu.
Is this the roof pitch calculator?
No. This page is ground or ramp grade from a rise and a run: percent, degrees, 1:x, and inches per foot. A roof pitch fixes the run at 12 and adds the area multiplier. That is the roof pitch calculator.