33 percent: about 3 to 1
33% is 18.26°, 1 in 3.03. It rises 3.96 inches per foot, a shade under a 4/12 roof pitch.
Over 100 feet of run it climbs 33 feet and the surface is 105.30 feet long. Measure materials for a bank like this along the slope, not from the plan.
An exact 3 to 1 slope, 4 inches of rise per foot, is 33.33%.
33% slope: rise over a distance
A 33% slope rises 33 feet in every 100 feet of level distance.
| Run (level distance) | Rise in inches | Rise in feet | Length along the slope |
|---|---|---|---|
| 1 ft | 3.96 in | 0.33 ft | 1.05 ft |
| 10 ft | 39.6 in | 3.3 ft | 10.53 ft |
| 20 ft | 79.2 in | 6.6 ft | 21.06 ft |
| 50 ft | 198 in | 16.5 ft | 52.65 ft |
| 100 ft | 396 in | 33 ft | 105.30 ft |
Worked example
33 ÷ 100 = 0.33. The angle is the arctangent of that: arctan(0.33) = 18.26°. As a ratio, 100 ÷ 33 = 3.03, so the slope is 1 in 3.03. Per foot, 0.33 × 12 = 3.96 inches.
Nearby grades in degrees
| Grade | Angle | Ratio | Rise per foot |
|---|---|---|---|
| 20% | 11.31° | 1 in 5 | 2.4 in |
| 25% | 14.04° | 1 in 4 | 3 in |
| 30% | 16.70° | 1 in 3.33 | 3.6 in |
| 33% | 18.26° | 1 in 3.03 | 3.96 in |
| 50% | 26.57° | 1 in 2 | 6 in |
| 100% | 45.00° | 1 in 1 | 12 in |
For any other rise, run or grade use the slope and grade calculator. The guide slope and grade for drainage and ramps covers how much fall each job needs.
Want to change anything else? The calculator above is the full Slope and Grade Calculator: edit any number and the results update instantly.
Tools & materials for this project
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Frequently asked questions
What is a 33 percent slope in degrees?
18.26 degrees. Divide the percent by 100 and take the arctangent: arctan(0.33) = 18.26°.
Is a 33 percent slope a 3 to 1 slope?
Very nearly. 33% is 1 in 3.03; an exact 3 to 1 slope is 33.33%, which is 18.43°.
How much does a 33% slope rise per foot?
3.96 inches for every foot of run, which is 39.6 inches over 10 feet and 33 feet over 100 feet.
Related sizes and guides
Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.