Gradient (Grade %) Calculator

Grade % = rise / run × 100. Convert to angle (degrees) and category (Cat 4-HC).

Result

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How to use this calculator

Measure rise (m gained) and run (horizontal m).
For a known length+grade route, set run = length × cos(angle) ≈ length.
Compare difficulty to grand-tour climbs.

About this calculator

A 5% grade means 5 m of rise per 100 m of run — that's arctan(0.05) ≈ 2.86°. Climbs are categorized in road racing by length × steepness² (rough proxy): Cat 4 climbs are 8-20 difficulty units, HC (hors catégorie, "beyond category") are 200+. The Mont Ventoux is HC at ~7.5% × 21 km. Note grade and angle differ — a 100% grade (45° slope) is a black-diamond ski run. Most paved roads stay under 20% even on alpine passes.

Frequently asked

Difference between grade and angle?+

Grade = rise/run (slope). Angle = arctan(grade). For small grades (<10%), they're ~equal; at 100% (45°) they diverge.

Is run length or horizontal distance?+

Strictly horizontal. For paved roads <20%, the difference between road length and horizontal is <2%. Use road length and you're close enough.

What's a "wall"?+

In cycling slang: any sustained section above ~15%. Anything above 20% is rare on paved roads (Koppenberg averages 12%, Mur de Huy maxes at 26%).

Do MTB grades work the same?+

Math is identical. But MTB climbs deal with traction, not just grade — a wet 8% root section can be unrideable while a dry 15% road climb isn't.

Why difficulty squared?+

Power required scales linearly with grade, but rider speed drops nonlinearly, so time × grade is roughly grade². It's an approximation, not the exact UCI formula.