Slope converter
Convert a slope between percent, degrees and the 1-in-N used on road signs. A 100% grade is 45°, not vertical.
That's about the same as a steep road sign. Over a kilometer on the map that climbs about 100 meters.
What it means
How steep is that?
Percent grade is rise over horizontal run. Road signs use the same definition, so a 10% hill climbs 10 m over 100 m of map distance, not of road.
Every unit
Your slope in every unit
Learn
Three things worth knowing
-
100% grade is 45 degrees
Because rise equals run. Percent grade has no upper limit: a vertical cliff is infinite percent but only 90°.
-
Railways counted in one-in-N
Victorian engineers wrote gradients as 1 in 100, meaning one unit up for a hundred along. It survives on British road signs and railway gradient posts.
-
Percent is not degrees
A 20% hill is 11.3°, not 20°. Treating grade as an angle badly overstates every steep slope you will ever drive up.
Shortcuts
Popular slope conversions
Background
About slope
A slope can be written as a percentage (rise over run × 100), an angle, or a ratio like 1 in 12. They are not proportional to each other: doubling the percentage does not double the angle.
Gentle slopes are nearly linear — 5% is 2.9°, 10% is 5.7° — but the two diverge fast after that.