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Slope & Grade Calculator

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

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-25 · v1.0.0

Market
Imperial · sales tax
39.37 ft3.28 ft
Schematic, drawn to the proportions you entered — not to scale on screen.

Slope grade

8.33 %

High confidence
Angle
4.76 degrees

At the values currently entered, the slope grade works out to 8.33 %. Note that rise sits at the low end of the range this calculator was checked against, so treat the output as indicative rather than settled. Figures are shown for United States, where IRC 2024 is the governing residential reference; switch the market above if you are building elsewhere.

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 — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

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

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.

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.