How this calculator works
Grade compares vertical rise with horizontal run, after both lengths are converted to the same unit. It does not use the diagonal travel distance. Multiplying the ratio by 100 expresses grade as a percentage; arctangent converts it to an angle from horizontal. Signed rise and grade distinguish uphill from downhill.
Formula
Grade fraction g = rise/run = tan(θ). Grade percentage number = 100g. Rise = g × run. Run = rise/g for g ≠ 0.
Worked example
A rise of 2 m over a horizontal run of 10 m gives g = 0.2, or 20%, and θ ≈ 11.3099 degrees. A 25% grade over 8 m of run rises 2 m.
Advertisement
Frequently asked questions
Is a 100% slope vertical?
No. A 100% grade has equal rise and run, so the angle is 45 degrees. A vertical line has no finite grade.
Should I enter the ramp length as the run?
No. Use its horizontal projection. The ramp length is the hypotenuse and would underestimate grade if used as the run.
Can I combine feet with metres?
Yes. Each length converts independently to metres before the ratio is calculated.