Ramp Calculator

A ramp's required length depends on how steep its slope is — and building codes like ADA set strict limits on that steepness for safety and accessibility. Enter your vertical rise and select an application type (such as ADA Standard for commercial use or a steeper loading ramp ratio) into the Ramp Calculator to find the required ramp length. Secondary outputs include the slope ratio, slope angle, and slope percentage.

inches

Total height difference from lower to upper level

Results

Required Ramp Length

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Slope Ratio

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Slope Angle

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Slope Percentage

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Frequently Asked Questions

How do you calculate the slope of a ramp?

Ramp slope is calculated as rise over run. For a 1:12 slope (ADA standard), you need 12 inches of ramp length for every 1 inch of vertical rise. The slope can be expressed as a ratio, percentage, or angle in degrees.

What is the ADA standard slope for wheelchair ramps?

The ADA standard slope for wheelchair ramps is 1:12, meaning 1 inch of rise for every 12 inches of horizontal run. This equals approximately 4.8 degrees or 8.33% grade, providing safe access for wheelchair users.

What are the minimum and maximum slopes allowed for ramps?

ADA allows a maximum slope of 1:12 for new construction. Gentler slopes like 1:16 or 1:20 are more comfortable. Steeper slopes up to 2:12 may be acceptable for residential use with assistance, while 3:12 is only suitable for unoccupied loading.

How to build a ramp that complies with ADA requirements?

ADA-compliant ramps must have a maximum slope of 1:12, minimum width of 36 inches, landings every 30 feet, handrails on both sides, and edge protection. The surface must be stable, firm, and slip-resistant with proper drainage.

What is the difference between residential and commercial ramp requirements?

Commercial ramps must meet strict ADA guidelines with 1:12 maximum slope. Residential ramps have more flexibility, allowing steeper slopes like 2:12 when users have assistance, though gentler slopes are always preferable for safety.

How long should a ramp be for a 12-inch rise?

For a 12-inch rise: ADA standard (1:12) requires 12 feet, comfortable slope (1:16) needs 16 feet, gentle slope (1:20) requires 20 feet. Residential occupied can use 6 feet, while loading ramps may use 4 feet.

What angle is a 100% slope?

A 100% slope equals a 45-degree angle, meaning the rise equals the run (1:1 ratio). This is extremely steep and not suitable for wheelchair access. Safe wheelchair ramps typically range from 2.4% to 8.33% grade.