Ramp Calculator
Calculate ramp run, sloped length, slope percentage, and angle from a rise and 1:n slope ratio.
Estimates for planning only — verify ramp dimensions against local accessibility codes (ADA, BS 8300, or equivalent) and consult a qualified professional before construction.
How it works
- 1Enter the rise — the vertical height the ramp must climb.
- 2Select a slope ratio (1:n). A 1:12 ratio means 12 units of run for every 1 unit of rise.
- 3The calculator computes run = rise × n, then the sloped length, slope %, and angle.
Use cases
- Designing a wheelchair-accessible ramp to meet ADA or local code requirements.
- Planning a loading-dock or delivery ramp for vehicles and pallet trucks.
- Estimating the space and materials needed for a garden or threshold ramp.
Frequently asked questions
What slope does the ADA require for ramps?
The ADA sets a maximum slope of 1:12 (about 8.3% or 4.76°). Gentler ratios such as 1:15 or 1:20 are easier to use and preferred where space allows.
How is ramp run calculated?
Run = rise × ratio. A 60 cm rise on a 1:12 ramp needs 60 × 12 = 720 cm (7.2 m) of run; the sloped length is √(rise² + run²) ≈ 7.22 m.
Is slope percentage the same as the ratio?
No. Slope % = (rise ÷ run) × 100. A 1:12 ratio is about 8.33%; a 1:8 ratio (the steepest common ramp) is 12.5%. Check your local code for the permitted maximum.
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