Slope Calculator
Framers think inches per foot, landscapers think percent, layout thinks degrees — enter the rate in whichever one you have and read all three back, plus the total fall over the run, the sloped (ramp) length, and the fall required to hit your drainage target.
Planning tool — results are estimates for quoting and ordering, not engineering or building-code advice.
Common questions
What slope do I need for drainage?
A common hardscape target is 2% positive drainage (about 1/4" per foot), with 1% as a typical minimum. The target field is editable — the calculator shows the fall your run needs to hit it.
How do I convert inches per foot to percent?
Divide by 12 and multiply by 100: 1/4" per foot is about 2.1%, 1" per foot is 8.3%. The calculator does the round trip between in/ft, %, and degrees automatically.
What's the ramp length for?
The sloped distance is longer than the horizontal run — that hypotenuse is what the ramp surface and handrail actually measure, so material comes off the sloped length, not the plan length.
Related: Stair calculator · Gravel calculator
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This solves one measurement. The Takeoff Builder prices the whole job.
Walk the rooms, enter dimensions, and formula-driven scope turns measurements into quantities, prices, and the estimate itself — from $20/mo, capped, no surprise bills.