Calculate concrete slope as a percent or fall per foot from rise and run, or find the drop for a slab or patio length using the common ¼ inch per foot.

Level distance, not the length along the sloping surface.

Result length unit

Concrete Slope Formula

The following formula is used to calculate the Concrete Slope. 

CS = H / L × 100
  • Where CS is the Concrete Slope (%)
  • H is the vertical rise or drop magnitude; use the same length unit as L
  • L is the horizontal run, not the sloping surface length

To calculate slope percentage, divide vertical change by horizontal run in matching units, then multiply by 100. Angle = atan(H/L); rise = run × grade/100; run = rise / (grade/100). This is a geometric calculation, not a drainage or accessibility compliance check.

How to Calculate Concrete Slope?

The following example problems outline how to calculate Concrete Slope.

Example Problem #1:

  1. First, determine the total height of the concrete slope.
    • The vertical rise or drop magnitude is 50 mm.
  2. Next, determine the total length of the concrete slope.
    • The horizontal run is 800 mm.
  3. Finally, calculate the Concrete Slope using the equation above: 

CS = H / L * 100

The values given above are inserted into the equation below and the solution is calculated:

CS = 50 / 800 * 100 = 6.25 (%)

Example Problem #2: 

For this problem, the variables needed are provided below:

vertical rise or drop magnitude = 60 mm

horizontal run = 700 mm

This example problem is a test of your knowledge on the subject. Use the calculator above to check your answer. 

CS = H / L * 100 = ?