Ramp Calculator
Calculate ramp rise, horizontal run, sloped length, ratio, grade percentage and angle. Enter the rise plus one known measurement.
Planning limit: this tool calculates geometry only. It does not certify accessibility or building-code compliance. Required slope, width, landings, handrails, edge protection, headroom and structural design depend on the ramp’s use and the locally adopted rules.
Ramp formulas
A ramp forms a right triangle. The vertical change is the rise, the level distance is the horizontal run, and the usable sloped surface is the ramp length.
- Ramp length = √(rise² + run²)
- Grade (%) = rise ÷ run × 100
- Angle = arctan(rise ÷ run)
- Slope ratio 1:N, where N = run ÷ rise
Calculated examples
| Rise and slope | Horizontal run | Sloped length | Grade / angle |
|---|---|---|---|
| 2 ft at 1:12 | 24 ft | 24.083 ft | 8.333% / 4.764° |
| 1 ft at 1:20 | 20 ft | 20.025 ft | 5% / 2.862° |
| 0.6 m at 1:12 | 7.2 m | 7.225 m | 8.333% / 4.764° |
| 30 in at 10% | 300 in | 301.496 in | 1:10 / 5.711° |
| 50 cm at 5° | 571.503 cm | 573.686 cm | 1:11.43 / 8.749% |
| 1 m rise, 13 m sloped length | 12.961 m | 13 m | 1:12.961 / 7.715% |
How to measure and use the result
- Measure the vertical height from the lower finished surface to the upper finished surface.
- Select the second value you already know: run, ratio, percentage, angle or sloped length.
- Use one length unit for every dimensional input. Ratios, percentages and degrees do not depend on the chosen unit.
- Add any required level landings separately; the calculated run and length describe only the inclined segment.
- Verify the completed design against the rules that apply to its actual use and location.
Related calculators
Use the Stair Calculator for risers, treads and stringer geometry, the Deck Calculator for decking materials, the Percentage Calculator for general percentage change and difference, or the Concrete Calculator when a separately designed ramp will be cast in concrete.