%\text{\%}

percent grade

Slopeexact by definition

Percent grade — rise per hundred of run. A 2% grade falls two metres in a hundred, and it is the unit road, rail and site drainage are designed in.

Watch out: Percent grade climbs without limit while an angle cannot: a 100% grade is 45 degrees, and a vertical face is an infinite percentage. Treating percent grade as though it were degrees understates steep slopes badly and is a common source of error in earthworks.

1 %\text{\%} 0.01 m/m\text{m/m}

One percent grade in every slope unit

0.01meter per meter (m/m)
1percent grade (%)this unit
10millimeter per meter (mm/m)
10per mille ()
0.01foot per foot (ft/ft)
0.12inch per foot (in/ft)