Wheelchair Ramp Slope

Three steps up to the front door, and someone in the house can't manage them anymore. The number that decides everything else is wheelchair ramp slope — how steep the ramp can be and still be usable by the person going up it. Get it right and they come and go on their own. Get it wrong and the ramp needs a second person every single time, which defeats the point of putting one in.

The good news is that the math is simple enough to do on the back of an envelope, and you only need one measurement to do it.

What slope does a wheelchair ramp need?

The standard is 1:12. One inch of rise needs 12 inches — a full foot — of ramp. A 12-inch rise gets a 12-foot ramp. A 24-inch rise gets 24 feet.

That ratio comes from the ADA 2010 Standards, Section 405. Nobody's inspecting your front porch, and those standards don't legally apply to a private home. But 1:12 is what the industry builds to, because it's based on what a person can actually push a chair up without help. It's a practical number before it's a regulatory one.

There's a second number most people miss. Cross slope is the side-to-side tilt of the ramp surface, and it needs to stay under 1:48. A ramp at the right steepness that also tips sideways will steer a chair toward the edge the whole way up, and whoever's using it has to correct for that the entire time. If a ramp feels wrong but the length looks right, cross slope is usually why. There's more on the full standard in our guide to what the ADA actually requires of a ramp.

How do you measure the rise?

Rise is the total height from the ground to the top of the door threshold. Not the height of one step, and not the height of the porch floor if there's a lip above it.

Rest a straight board on the threshold and run it out over the ground where you want the ramp to end. Put a level on it. Once the board sits level, measure straight down from its underside to the ground. That number, in inches, is your rise.

No long board and level handy? Count steps instead. A typical exterior step rises about 7 inches, so step count multiplied by 7 gets you close. It's an estimate rather than a measurement, but it's close enough to know what you're dealing with.

Then the conversion is the easy part: your rise in inches is your ramp length in feet. A 21-inch rise needs about 21 feet of ramp. That's the whole calculation.

Rise-to-length chart

If you'd rather just look it up, here's the same math laid out at 1:12. Step counts assume the typical 7 inches per step.

What length ramp do I need for 3 steps?

Three steps is the most common front entrance we see, and it's usually about 21 inches of rise. That means roughly 21 feet of ramp.

People are often surprised by that. Three steps doesn't sound like much, and 21 feet sounds like a lot. Both are true at once — that's simply what a safe slope costs in length.

It's also why the small folding ramps sold online rarely work for a real set of front steps. A 6-foot portable ramp over 21 inches of rise works out to roughly a 1:3.5 slope. That's steep enough that nobody should be going up it alone, and steep enough that going back down is the harder direction.

When does a ramp need a landing?

Once a single run climbs more than 30 inches, it needs a level landing before it continues. A landing has to be at least 60 inches long and at least as wide as the ramp itself. Where the ramp changes direction, that landing needs to be a full 60 by 60 inches so a chair can turn on it.

Landings do two jobs. They give someone a flat place to stop, which matters more than people expect on a long climb. And they're what lets a ramp turn a corner instead of running straight out forever.

Handrails come in around the same point. Once the rise clears 6 inches the ramp needs rails, and they belong 34 to 38 inches above the ramp surface. Ours come with handrails on both sides as standard, plus edge protection along the runs and landings so a caster can't drop off the side.

Does a 21-foot ramp really take 21 feet of yard?

No — and this is the single most common worry we hear on the phone. People picture a ramp shooting straight out from the porch and halfway across the front lawn.

Modular ramps turn. They switch back on themselves, run along the front of the porch, or wrap around a corner of the house. A 21-foot run folded into a switchback takes a footprint closer to 11 feet by 5 feet. Most of our installs use far less yard than the homeowner pictured when they called, and plenty of them sit along the side of the porch where they're barely visible from the street.

Working out that layout is part of the free on-site assessment, because the right configuration depends on where the door is, which way it swings, and what's in the way.

Is a steeper ramp ever okay?

Sometimes, with caveats worth being straight about.

Short portable ramps are often rated at 2:12 or even 3:12 for occupied use, and steeper still for loading an unoccupied chair into a vehicle. Those ratings assume someone is assisting. A power chair with good torque handles more slope than a manual chair, and a strong person pushing handles more than someone going up on their own.

What we won't do is tell you what slope suits a specific person's strength — that's a question for their physical or occupational therapist, and an OT home assessment is a genuinely useful thing to ask for. What we can tell you is that 1:12 is the ratio that works for the widest range of people without assistance, which is why it's what we build to.

What ramp slope looks like on Owensboro porches

A lot of the housing around Owensboro and Daviess County was built with a concrete stoop and three or four steps straight up to the front door, no handrail on either side. That's a 21- to 28-inch rise landing on a stoop barely big enough to stand on while you work the storm door.

Those entrances almost never have room for a straight ramp, and the front door often opens outward over the top step, which eats the space a ramp landing needs. It's solvable. The ramp turns, and the top platform gets built out at doorway level so the door has somewhere to swing. Split-level entries are the other common one around the county, and those usually route along the side of the house rather than out the front.

You don't have to measure it yourself

If the board-and-level routine sounds like one more thing on an already bad week, skip it. Send us a photo of the front entrance and we'll size it from there. A picture showing the steps and the ground around them tells us most of what we need.

From there it's short. We come out and do a free on-site assessment, confirm the rise, and lay out a configuration that fits the yard. Installation is usually within 24 to 48 hours of the call, and same-day is sometimes possible when someone's being discharged from the hospital. The ramp itself is commercial-grade aluminum, 36 inches wide, rated to 800 pounds, with a non-slip surface and handrails on both sides.

Nothing gets drilled or bolted into the house. The system is freestanding, so when you're done with it we come back and take it out, and the entrance looks like it did before we showed up. Renting runs $100 to install, $75 a month, and $100 to remove, with no minimum rental period and maintenance included — there's a full breakdown of the rental cost here. That $100 install fee covers delivery within 50 miles of Owensboro.

If you're at the earlier stage of working out whether a ramp is even the right answer for a parent's front steps, our guide on choosing a ramp for a parent's stairs covers the decision rather than the math.