Calculator
How Long Should Your Wheelchair Ramp Be?
Ramp length is not a judgment call — it is arithmetic. Measure the rise from finished ground to the top of the threshold, choose a slope, and the length follows. Use the calculator below, then check the worked examples to see what the number means for your yard.
Ramp length needed
24.0 ft of ramp run
- Ramp sections
- 1
- Intermediate landings
- 0
- Total footprint to plan
- about 34 ft
Footprint includes 5-foot landings and 5 feet of clear space at the top and bottom. Local codes may differ; confirm with your building department or installer before ordering material.
How the math works
Slope is expressed as a ratio of run to rise. A 1:12 slope means one inch of vertical rise needs twelve inches of ramp. So a 24-inch rise needs 288 inches — 24 feet — of ramp run, before landings.
The ADA sets 1:12 as the maximum slope for new public ramps and limits any single run to 30 inches of rise before a level landing. Private homes usually are not covered by the ADA, but 1:12 remains the practical standard because it is what most people can actually manage in a manual wheelchair.
How to measure your rise (the step most people get wrong)
Rise is the vertical distance from the finished ground where the ramp will start to the top of the door threshold. Do not estimate it by counting steps — step heights vary, and porches settle over time.
- Set a straight board or long level on the threshold, extending out over the ground.
- Level it with a bubble level or a level app on your phone.
- Measure straight down from the bottom of the board to the ground at the point where the ramp would end.
- Repeat after rain or check for low spots — pooling water under a ramp shortens its life.
If the ground slopes away from the house, your rise changes along the ramp's path. Measure at the actual end point of the planned run, not directly below the door.
For any ramp used independently, 1:12 is the ceiling — go gentler when you have the room.
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Worked examples: three real scenarios
Example 1: Two steps into a ranch house
A front stoop with two 7-inch steps gives a 14-inch rise. At 1:12, that needs 14 feet of ramp run with no intermediate landings. Add 5 feet of level space at the bottom and the top platform, and you are planning for roughly 24 feet of total footprint. This is squarely in modular aluminum territory, and a portable ramp is also a legitimate option for rises this small.
Example 2: A porch 30 inches above grade
A 30-inch rise needs 30 feet of ramp at 1:12 — right at the 30-inch single-run limit, so many designs break it into two 15-inch sections with a resting landing between them. Total footprint with landings and end clearances is around 40 feet. On a narrow lot, this is where a switchback layout (the ramp doubles back on itself) or a porch lift starts to make more sense than a straight run.
Example 3: A 48-inch rise to a main-floor entry
At 48 inches of rise, 1:12 means 48 feet of ramp run, one required landing at 30 inches of rise, and a total footprint approaching 60 feet. Very few front yards absorb that gracefully. The realistic options are a switchback ramp along the house, a vertical porch lift with a footprint of roughly 5 by 5 feet, or rethinking which door becomes the accessible entrance — a garage or side entry at a lower grade often cuts the rise in half.
Ramp run only. Add 5 ft for each intermediate landing plus 5 ft of clear level space at the top and bottom.
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What to do with the number
Take the length into your quotes. Modular aluminum ramps are usually priced per linear foot plus landings, so a contractor quoting a lump sum should still be able to tell you the run and landing count they designed to. If two quotes differ wildly, it is often because one designed a steeper ramp.
- Confirm the slope in writing, not just the total price.
- Ask whether handrails are included — at 1:12 they usually should be.
- Check that the top landing is level and at least 5 feet deep so the door can swing outward.
- Ask about permits. Permanent ramps generally need one; portable ramps generally do not.
Frequently asked questions
How long does a ramp need to be for three steps?
Three standard steps is roughly 21 to 24 inches of rise, which needs 21 to 24 feet of ramp at the recommended 1:12 slope. That surprises most people, and it is the main reason porch lifts get considered for tall rises on small lots.
What slope is legal for a home?
Private homes are generally not governed by the ADA, so 1:12 is a strong recommendation rather than a legal requirement in most jurisdictions. Permanent ramps still usually require a permit and must meet local building code, which often references 1:12. Check with your building department before you build.
When do I need a landing?
Plan a level landing at least every 30 inches of rise, at the top of the ramp, and anywhere the ramp changes direction. Landings should be at least 5 feet by 5 feet so a wheelchair can turn without a wheel dropping off the edge.
Is a steeper ramp acceptable if someone is pushing?
Slopes up to about 1:10 are sometimes used for short assisted rises, and portable threshold ramps go steeper still. Steeper ramps demand real strength from the person pushing and are unsafe for independent self-propelled use. If the person needs to use the ramp alone, stay at 1:12 or gentler.
Does ramp length change the price much?
Yes — length is the primary cost driver. Modular aluminum ramps are commonly quoted per linear foot, so doubling the rise roughly doubles the material cost and adds landings on top.
What slope ratio should I use for a power wheelchair or scooter?
Power wheelchairs and scooters handle 1:12 well, and many manufacturers rate their devices for steeper grades — but the device rating assumes dry, clean surfaces and a skilled driver. For a permanent home ramp, 1:12 remains the safe default, and 1:16 is a comfortable upgrade when space allows. Check your device manual's maximum incline before going steeper.
How do I convert slope to degrees or percent?
A 1:12 slope is about 4.8 degrees or 8.33 percent grade. Divide the rise by the run and multiply by 100 to get percent grade; 1:12 gives 1 ÷ 12 × 100 = 8.33%. Most building departments and ADA documents use the ratio form, so keep your notes in ratios.
Can I use the calculator for a shed, curb, or vehicle ramp?
The math is the same, but the right slope differs. Unoccupied loading ramps and vehicle ramps are commonly built much steeper than 1:12 because nobody is riding them. For any ramp a person will ride or walk, stick with the occupancy-based slopes in the calculator.
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