Plumbing & Layout
Rolling Offset Formula
Solve rolling offsets for pipe: true offset, travel and setback for 45°, 22½°, 60° and 11¼° fittings.
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Roofing & Exterior
Ramp Calculator
Plan a wheelchair, scooter or equipment ramp. Enter the height it needs to climb and the slope ratio to get the ramp length, angle and number of landings.
What is a ramp calculator?
A ramp’s slope is expressed as a ratio of rise to run. A 1:12 slope climbs 1″ for every 12″ of horizontal distance — the steepest slope allowed for accessible public ramps in the US. This calculator turns your rise into the footprint you need.
How does it work?
Run = rise × ratio. The ramp surface is the hypotenuse of rise and run, and the angle is the arctangent of 1 ÷ ratio. Accessibility guidelines limit each run to 30″ of rise, so landings are added in between. The same triangle maths appears in the Rolling Offset Formula. Pouring a concrete ramp? Estimate the slab with the Cubic Yard Calculator.
What information is needed?
- Total rise in inches
- Slope ratio you want to build to
How to use the Ramp Calculator
- Measure from the ground straight up to the top of the threshold or deck.
- Choose a slope — 1:12 is the maximum for wheelchair users.
- Select Calculate.
- Add landing depth to the run for your total footprint.
The formula
In plain terms, here is the calculation the tool runs:
Run = Rise × Ratio
Ramp length = √(Run² + Rise²)
Angle = atan(1 ÷ Ratio)
- Ratio
- 12 for 1:12, 16 for 1:16, etc.
- Landings
- One every 30" of rise
Worked example
Example
A 24" rise to a front door at 1:12.
- 24 × 12 = 288" = 24 ft of run
- √(288² + 24²) = 289" ≈ 24.1 ft of ramp
- atan(1/12) = 4.76°
A 24 ft run with no intermediate landing, plus top and bottom landings.
Frequently asked questions
Is 1:12 required for home ramps?
Private residences are not always bound by ADA, but 1:12 or gentler is strongly recommended for wheelchair users.
How wide should a ramp be?
At least 36″ clear between handrails.
Can a ramp turn?
Yes, at a landing. A switchback or L-shaped ramp saves space where a straight run will not fit.
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