Climb difficulty calculator

How the calculator works

Type the length of the climb, the height it gains and how high the top is above sea level. The calculator gives the climb a score. The bigger the score, the harder the climb.

Steep climbs score far more than gentle ones. The sum squares the height, so a climb that gains twice the height over the same distance scores four times as much.

A high top adds a little more, as climbing is harder in thin mountain air. Only the part above 1,000 m counts, and each 1,000 m above that adds one point.

The FIETS index

Fiets is the Dutch word for bike. It is also the name of a Dutch cycling magazine, which made this score to compare climbs. Many ride apps and climb guides still use it.

Multiply the height gained by itself. Divide that by the length in metres times 10. Then, if the top is over 1,000 m, add the height above 1,000 m divided by 1,000.

For example, a climb that gains 160 m over 3 km scores 160 times 160, which is 25,600, divided by 30,000. That comes to 0.85.

How the real climbs were scored

The table scores some of the climbs on this site with the same sum. It uses the length and height from each climb's own page. The heights of the tops come from Wikipedia.

Every climb in England tops out below 1,000 m, because the highest point in England is Scafell Pike at 978 m. So the English climbs get nothing extra for height.

What the score does not show

The score treats a climb as one even slope. A climb with a very steep stretch can feel much harder than its score says. Heat, wind and the gears on your bike change how it feels too. Use the score to compare climbs, not to judge yourself.

Where the numbers come from

The sum is set out on the Runalyze climb score page and the ActivityLog2 climb score guide. The ActivityLog2 guide gives the 160 m example above, and this calculator gets the same answer. A few sites write the sum a little differently. This calculator uses the version that matches those worked examples.

PJAMM Cycling explains what the score leaves out, such as heat and wind. The heights of the tops are from Wikipedia for Alpe d'Huez, Mont Ventoux, the Col du Tourmalet, the Stelvio Pass and Scafell Pike.