What's a typical maximum slope for a wheelchair ramp?

The ADA requires a maximum running slope of 1:12 (about 8.33%, roughly 4.8°) for accessible ramps — this calculator's first example is exactly that ratio.

What slope do driveways typically need for drainage?

A minimum of about 1-2% grade is commonly recommended so water sheets off rather than pooling, while over 15-20% starts to become difficult to drive and park on safely, especially in icy conditions.

Is grade percent the same as degrees?

No — they're related but not linearly the same (a 100% grade is a 45° angle, not 90°). This calculator gives you both so you can use whichever unit your project's spec calls for.

Measurements & Conversions

Slope & Grade Calculator

Convert a rise and run measurement into slope percentage and angle in degrees.

Answers as you typeNo submit button
Every formula citedNamed published standards
Calculated in your browserNo account, nothing uploaded

SettingsSettings for this calculationUS

Market

Imperial · sales tax

Rise

The vertical change in height over the run.

Measure the vertical difference between the two ends of the slope.

Run

The horizontal distance over which the rise occurs.

Measure the horizontal distance between the two ends of the slope.

Slope grade

8.974 %

High confidence

Angle: 5.13 degrees

Then change the inputs to see how far the answer moves.

Show calculation logic

How this was calculated

Formula source(s)

Grade percent = (rise / run) x 100; angle in degrees = arctangent(rise / run)

Inputs used

Rise: 3.5 ft
Run: 39 ft

Intermediate steps

Angle: 5.13 degrees

Final result8.97 %

What this calculation does not cover

Run is taken as the true horizontal distance between the two ends, and nothing converts a tape laid along the sloping face into that horizontal — measure along the surface instead and the grade reads lower than the ground really is, with the gap widening as the slope steepens.
Rise is read as a magnitude only, so a drop and a climb of the same size return the same positive grade and a negative entry is floored to zero; which end is higher stays your own note rather than something the answer carries.
Both figures describe a single straight line drawn between the two points you measured, so any crest, dip or bench sitting between them is averaged away, and cross-fall across the width of a drive or path is not part of the arithmetic at all.
The output covers grade percent and the matching angle; the sloping distance itself — what you would order ramp board, handrail or edging against, and always longer than the run — is not worked out, nor is the result expressed as the 1-in-X ratio that specifications are often written in.
No ceiling is applied to the outcome: a 2% fall and a 45% bank come back with identical confidence, and the accessible-ramp and driveway grade figures quoted in the questions below are context for reading your number, not a test the calculation runs against it.

Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Sources checked 2026-09-05 · in the site-wide review of 2026-09-06 · v1.0.1

Regulatory standards & verification citations1

Grade percent = (rise / run) x 100; angle in degrees = arctangent(rise / run)

Cite this page

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Now that you have the number

These guides cover the work this quantity is for — the first ones run this calculator inside the section that raises the question.

Building a Pedestal Paver Terraceuses this calculator
The deck falls, the terrace cannot. That disagreement is measured in millimetres of pedestal, and it is a schedule of heights rather than one height.
Building an Accessible Rampuses this calculator
A ramp is one fixed vertical rise divided among runs, landings and handrails - spend that slope allowance before the first form board goes down.
Building Steps Into a Garden Slopeuses this calculator
Dividing an awkward bank into equal risers, matching the going to the ground you actually have, and laying every tread to a fall so it drains instead of icing.

Worked examples: Gravel driveway — step 1 of 8 · Privacy fence — step 1 of 7

How to calculate slope & grade in 3 steps

RiseThe vertical change in height over the run.
RunThe horizontal distance over which the rise occurs.
Slope gradeThe tool computes the slope grade from those figures and shows the formula, its sources, and a confidence rating alongside it.

Slope grade by rise

Page defaults, not your figures above.

Rise	Slope grade (%)
2 ft	5.08
3 ft	7.62
4 ft	10.2
5 ft	12.7
6 ft	15.2

Frequently asked questions

What's a typical maximum slope for a wheelchair ramp?: The ADA requires a maximum running slope of 1:12 (about 8.33%, roughly 4.8°) for accessible ramps — this calculator's first example is exactly that ratio.
What slope do driveways typically need for drainage?: A minimum of about 1-2% grade is commonly recommended so water sheets off rather than pooling, while over 15-20% starts to become difficult to drive and park on safely, especially in icy conditions.
Is grade percent the same as degrees?: No — they're related but not linearly the same (a 100% grade is a 45° angle, not 90°). This calculator gives you both so you can use whichever unit your project's spec calls for.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — a confirmed fix gets a permanent check of its own, so the same mistake cannot come back.