Wheelchair Ramp Sizing Guide: How to Choose the Right Ramp Length
The single most common question we've answered since 1999 is: "How long does my ramp need to be?" The answer comes down to two numbers, the height you need to climb (the rise) and the slope ratio that's safe for how the ramp will be used. This guide walks you through both, with sizing charts and specific recommendations for threshold ramps, portable ramps, and modular ramp systems.
Prefer to have the math done for you? Our free Ramp Wizard calculates slope and recommends a ramp from your measurements.
Step 1: Measure Your Rise
Rise is the total vertical height from the ground straight up to the top surface the ramp must reach: a door threshold, porch, deck, or vehicle floor. Measure it with a tape measure held level, from the ground straight up to the landing surface. If the ground slopes away from the house, measure at the point where the ramp will end, not at the base of the steps. Write the rise down in inches; every sizing decision that follows depends on it.
Step 2: Pick the Right Slope Ratio
Slope is expressed as a ratio of ramp length to rise. A 1:12 slope means 12 inches (1 foot) of ramp for every 1 inch of rise. The right ratio depends on who is using the ramp and how:
- 1:12 Occupied, independent use (ADA standard). One foot of ramp per inch of rise. Required for businesses, churches, and schools, and the safest choice for anyone rolling up a ramp unassisted in a manual wheelchair. See our ADA slope guide for full commercial requirements.
- 2:12 Occupied, assisted use. One foot of ramp per 2 inches of rise. Often acceptable for residential settings when a caregiver assists, or for power chairs and scooters rated for steeper grades. Always check your equipment manual's slope limit first.
- 3:12 Unoccupied loading only. One foot of ramp per 3 inches of rise. Only for rolling an empty wheelchair or scooter into a vehicle while the user transfers separately.
Wheelchair Ramp Sizing Chart
Find your rise in the left column, then read across for the minimum ramp length at each slope ratio.
| Rise (inches) | 1:12 — Independent Use | 2:12 — Assisted Use | 3:12 — Unoccupied Loading |
|---|---|---|---|
| 2" | 2 ft | 1 ft | — |
| 4" | 4 ft | 2 ft | 16 in |
| 6" (one step) | 6 ft | 3 ft | 2 ft |
| 12" | 12 ft | 6 ft | 4 ft |
| 18" | 18 ft | 9 ft | 6 ft |
| 24" (porch) | 24 ft | 12 ft | 8 ft |
| 30" | 30 ft* | 15 ft | 10 ft |
| 36"+ | 36 ft+* | 18 ft+ | — |
*ADA limits each ramp run to a 30-inch rise and requires a level rest landing every 30 feet of run, so longer ramps are built as multiple runs with landings and switchbacks — this is where modular systems shine.
Threshold Ramps: Rises Up to 6 Inches
Threshold ramps are compact wedges that sit against a doorway lip, raised landing, or single step. Because the rises are small, they don't follow the 1:12 rule - instead, match the ramp's rated height range to your measured rise:
- Up to 2": an angled entry plate - a one-piece aluminum plate ideal for door thresholds and sliding-door tracks.
- Up to 4.75": a rubber threshold ramp - heavy duty recycled rubber that stays put without fasteners and can be trimmed to fit.
- Up to 6": an adjustable aluminum modular entry ramp - supports taller single steps.
Measure the threshold height at its tallest point, and check whether the door swings out over the ramp location - out-swinging doors need a ramp that sits clear of the door's arc. For a deeper walkthrough, see our Threshold Ramp Selection Guide.
Portable Ramps: Rises Up to About 30 Inches
Portable folding ramps come in fixed lengths - typically 2 to 10 feet, and fold like a suitcase for transport. Because the length is fixed, sizing works backwards from the chart above: divide your rise by the slope ratio to get the minimum length.
For example, a 15-inch rise used independently needs 15 feet of ramp at 1:12,longer than portable ramps go, so a modular system is the better fit. But the same 15-inch rise with caregiver assistance needs only about 7.5 feet at 2:12, which an 8-foot singlefold ramp handles. For vehicle loading of an unoccupied scooter, a 10-foot trifold ramp covers rises up to 30 inches at 3:12 (which is steeper than recommended).
Two more sizing checks before you buy: confirm the ramp's weight capacity covers the user plus the mobility device (power chairs alone can exceed 350 lbs), and confirm the usable width between the ramp's side rails fits your wheelbase most portable ramps offer about 29–30 inches of clear width. Most portable ramps have a 800 lbs weight capacity.
Modular Ramps: Rises Over 20 Inches and Permanent Access
Once your rise passes roughly 20 inches, three or more steps, or a full porch a modular aluminum ramp system is usually the right answer. Modular ramps are built from pre-engineered sections, platforms, and handrails, so they can reach any length the 1:12 rule demands, turn corners, and switch back to fit compact yards. They install in hours without concrete footers, and they're engineered to meet residential ramp code.
Sizing a modular system at 1:12 is simple: ramp length in feet = rise in inches. A 24-inch porch needs 24 feet of ramp, plus a 60-inch level landing at the top and bottom, and a 5' × 5' platform at every turn. Handrails are recommended on both sides for any rise over 6 inches. For commercial projects, our ADA-compliant Pathway HD systems add the 36-inch clear width, landing, and handrail specs the ADA requires.
Because layout matters as much as length, we recommend letting the Ramp Wizard or a specialist at 866-491-1110 configure modular systems a free service that ensures the sections, platforms, and handrails arrive as one complete kit.
Quick Reference: Which Ramp Type Fits Your Rise?
| Your Rise | Best Ramp Type | Typical Use |
|---|---|---|
| ½" – 6" | Threshold ramp | Doorways, sliding doors, single steps |
| 2" – 30" | Portable folding ramp | Steps, curbs, vehicle loading, travel |
| 10" and up | Modular ramp system | Porches, decks, multi-step entries, daily home access |
Frequently Asked Questions About Wheelchair Ramp Sizing
How long should a wheelchair ramp be for 3 steps?
Three standard steps total roughly 21–22 inches of rise (steps average about 7–7.5 inches each). At the 1:12 ratio for independent use, that calls for a 21–22 foot ramp, a job for a modular system. With caregiver assistance about 8 feet is the minimum. Always measure your actual total rise rather than assuming; step heights vary.
What is the correct slope for a wheelchair ramp?
The ADA standard is the safest choice for anyone using a ramp independently which is 1:12: one foot of ramp length for every inch of rise. A 2:12 slope may be acceptable for assisted residential use, and 3:12 only for loading unoccupied equipment. Steeper than the equipment manufacturer's rating is never safe.
How do I measure the rise for my ramp?
Hold a tape measure level and measure straight down from the top landing surface (threshold, porch floor, or vehicle floor) to the ground where the ramp will end. If the ground is uneven or slopes away, measure at the ramp's actual endpoint. Use inches - the sizing math is built around them.
What size threshold ramp do I need?
Measure your threshold or step height at its tallest point, then choose a ramp rated for that height: angled entry plates handle up to 2 inches, rubber threshold ramps up to 4.75 inches, and adjustable aluminum entry ramps up to 6 inches. Also check clearance if your door swings outward over the ramp location.
How wide should a wheelchair ramp be?
ADA requires 36 inches of clear width between handrails, and it's a sound target for home ramps too. For portable ramps, check the usable width between side rails - typically around 29–30 inches against your wheelchair or scooter's wheelbase, and add a couple of inches of margin for comfortable tracking. Most standard wheelchairs or scooters will fit comfortably on 29-30 inch wide ramps.
Can a ramp be too long?
Longer is gentler, so extra length is rarely a safety problem - but ADA limits any single run to a 30-inch rise and requires a level rest landing at least every 30 feet. Very long ramps are broken into multiple runs with rest platforms, which is exactly what modular systems are designed for.
What weight capacity does my ramp need?
Add the user's weight to the mobility device's weight, then add a safety margin. Manual wheelchairs run 15–50 lbs, but power wheelchairs and scooters commonly weigh 150–400 lbs on their own. Most quality aluminum ramps are rated 600–800 lbs or more, but always confirm the rating on the specific model.
Do residential ramps have to meet ADA requirements?
Not typically. ADA applies to public and commercial spaces, not private homes. But inspectors and contractors treat ADA specs as the gold standard, and local residential codes still apply, especially for permanent ramps. Our Residential Ramp Code Guide covers the differences in greater detail.
What length ramp do I need to load a scooter into a van?
Measure from the ground to the van's floor or cargo deck - typically 24–30 inches. Loading an unoccupied scooter at 3:12 needs 8–10 feet of ramp; if the user rides up with assistance, size at 2:12 (12–15 feet) or use a vehicle lift instead. Check your scooter manual for its maximum rated slope before choosing.
Is it better to buy a ramp that's slightly longer than the chart says?
Yes, when in doubt, size up. A longer ramp gives a gentler slope, which means less effort for manual wheelchair users, better traction in rain or frost, and more margin for heavier power chairs. The chart lengths are minimums, not targets.
Still Not Sure? Get Sized for Free
Every project has a wrinkle the charts can't capture sloped yards, tight landings, out-swinging doors. Run your measurements through the Ramp Wizard for quick answers.