Slope and Grade Calculator
Convert slope between percent, ratio, degrees and fall over a run, and see the fall for any run length.
Slope & Grade Calculator
Percent, ratio, degrees and fall over a run are four ways of writing one slope. Drainage is specified in all four depending on who drew it, so this converts between them and checks the fall.
| Percent | — |
|---|---|
| Ratio | — |
| Angle | — |
| Fall over the run | — |
| Per 10 ft / per metre | — |
| Slope length (hypotenuse) | — |
Percent is rise ÷ run × 100. Ratio “1 in 20” is the same as 5%.
Degrees are arctan(rise ÷ run) — note that degrees and percent only agree at zero and diverge
as the slope steepens, which is why mixing the two on one drawing causes trouble.
Common planning references: paved surfaces are usually drained at about 1–2%, and finished grade
is typically pitched away from a building for the first few feet. Accessible routes and ramps are
governed by accessibility regulations with their own limits and landing rules. Every one of those is
set by the applicable code and by the design, not by this page — confirm the required figure for
your project rather than taking a number from here.