Slope & Grade Calculator (% and Degrees)
Compute slope percentage ($\%$), angle of inclination ($^\circ$), $1:X$ gradient ratio, and sloped length from vertical rise and horizontal run.
What does the Slope & Grade Calculator do?
The Herramix Slope & Grade Calculator is designed for civil engineers, surveyors, architects, and plumbers designing wheelchair ramps, roof pitches, gravity drainage pipes, and highway grades.
Enter the vertical rise ($H$) and horizontal run ($D$) using the same length unit (meters, centimeters, feet, or inches). The calculator immediately outputs the slope grade in percent, the inclination angle in degrees, the $1:X$ gradient ratio, and the true sloped distance ($\sqrt{H^2 + D^2}$).
Usage example
Scenario: Designing an access ramp that rises $0.80\text{ m}$ over a horizontal run of $10\text{ m}$.
Result: The ramp has an $8\%$ grade, an angle of $4.57^\circ$, a $1 : 12.5$ ratio, and a sloped surface length of $10.03\text{ m}$.
Frequently Asked Questions
How do you calculate slope percentage (%)?
Divide the vertical rise ($H$) by the horizontal run ($D$) and multiply by 100: $\text{Slope (\%)} = (H / D) \times 100$. For example, a pipe dropping $2\text{ cm}$ per $100\text{ cm}$ of horizontal run has a $2\%$ slope.
How many degrees is a 100% slope?
A 100% slope equals 45° (not 90°), because vertical rise equals horizontal run ($H = D$, and $\arctan(1) = 45^\circ$).
What slope is typical for drainage pipes and accessibility ramps?
Gravity sewer and drain pipes typically use a 1% to 2% slope ($1/8$ to $1/4$ inch per foot). Accessibility ramps typically require a maximum grade between 5% (1:20) and 8.33% (1:12).