What units should I use for rise and run?

Use any consistent unit — both rise and run must be in the same unit (e.g., both in meters or both in feet). The calculator works with any unit because gradient is a dimensionless ratio.

What is percent grade?

Percent grade is rise divided by run, multiplied by 100. A 5% grade means the terrain rises 5 units for every 100 units of horizontal distance. Roads in mountainous areas often range from 5% to 10%.

What does 1-in-X notation mean?

A slope of 1-in-X means the surface rises 1 unit for every X units of horizontal distance. For example, 1-in-12 is the minimum ADA ramp slope — 1 cm rise per 12 cm of run.

What is a typical maximum slope for wheelchair ramps?

The ADA standard requires a maximum slope of 1:12 (rise:run), which equals 8.33% grade and 4.76 degrees. Some codes allow 1:8 (12.5%) for very short ramps.

Can the rise be larger than the run?

Yes — slopes steeper than 45 degrees have a rise greater than the run. The angle will exceed 45 degrees and the percent grade will exceed 100%. This is common for stairs and steep terrain.

How accurate are the results?

Results are calculated using standard trigonometry (arctan) and are accurate to the precision of your inputs. Displayed values are rounded to 4 decimal places or 2 decimal places for readability.

Slope Gradient Calculator

Name: Slope Gradient Calculator
Availability: InStock
Author: Nham Vu

Enter rise and run to instantly compute slope angle, percent grade, rise:run ratio, and 1-in-X notation.

Enter Rise and Run

Use any consistent unit for both values (meters, feet, inches, etc.).

Vertical Rise

units

Horizontal Run

units

Slope Diagram

Slope Results

Enter rise and run to see results

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Summary

Enter rise and run to instantly compute slope angle, percent grade, rise:run ratio, and 1-in-X notation.

How it works

Enter the vertical rise (height gained or lost) in the Rise field.
Enter the horizontal run (horizontal distance traveled) in the Run field.
The calculator computes gradient = rise / run, then derives all other notations.
Slope angle is calculated as arctan(rise / run) converted to degrees.
Percent grade is gradient multiplied by 100.
1-in-X notation is the reciprocal of the gradient (run per unit of rise).

Use cases

Verify ramp gradients comply with accessibility standards (e.g., 1:12 ADA ramps).
Calculate road grade for highway and driveway design.
Determine drainage slope for gutters, pipes, and landscaping.
Check roof pitch and its percent grade equivalent.
Convert surveying measurements between angle, percent, and ratio formats.
Assess hillside steepness for construction or outdoor recreation planning.
Confirm conveyor belt or chute incline angles for material handling.
Evaluate ski slope or mountain trail difficulty ratings.

Frequently Asked Questions

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Last updated: 2026-05-23 · Reviewed by Nham Vu