Slope Percentage Calculator

Convert a rise and run into slope as a percentage, ratio and angle.

Slope (%) 15

Angle (°) 8.531

Formula: slope% = rise ÷ run × 100

Step-by-step with your numbers:

1. Values used:

2. Rise (vertical) = 3

3. Run (horizontal) = 20

5. Slope = 15%

6. Angle = 8.531°

Did we solve your problem today?

Grade or slope as a percentage is widely used for roads, ramps and roofs.

The math behind it

A slope percentage is rise ÷ run × 100. A 100% slope is a 45° angle (rise equals run).

Rise 3 over run 20 → 3 ÷ 20 × 100 = 15% (about 8.5°).

Is 100% slope vertical?

No — it is 45°. A vertical slope is undefined (infinite percentage).