How we measure

What we measure

• The line: runs and lifts are drawn by the contributors of OpenStreetMap. The ways of a run with the same name and difficulty that touch (within 40 m) become one run, and its line is the longest chain of them downhill. Runs without a name, areas and runs under 60 m have no page.
• Length: horizontal, along that line, not along the slope.
• Top, bottom and vertical drop: the altitude of the relief at the first and last points of the line that have one, sampled every 10 m.
• Average gradient: the vertical drop divided by the length, in per cent. Where the relief does not reach all the line, over the stretch it reaches.
• Steepest 20 m: each 10 m step counts as the median of the five around it (50 m), so that a single step of the ground, such as a road’s cut or a bank, does not count.
• Rankings: among the named runs of the area measured by GeoPeaks. Ties share a place.
• Lifts: length and rise from station to station on the relief; type, capacity, seats and time as OpenStreetMap has them, when it has them.

Sources and versions

Each area is measured on one version of the data. A new version can change its numbers.

The relief, by country

Each country’s own elevation model of the bare ground, where we have one, read at the resolution below and sampled onto a grid of 2 m, the one the 3D view is drawn on. The Copernicus model, a surface model of 30 m, lies around it and fills its gaps.

The numbers are measured on the relief as the 3D view draws it. In the corridor of a run it is shaped the way a groomed run is: levelled across, smoothed along the line over about ±10 m, small rises and counter-slopes removed. So a number describes the run as drawn: close to the ground, but not a survey of it.

Limits

• The line and the difficulty are as OpenStreetMap has them: a line drawn beside the real run, or a run changed since, changes the numbers.
• A steep pitch shorter than about 30 m reads gentler than it is, because of the 2 m grid, the shaping of the corridor and the median over 50 m.
• The relief has no bridges or tunnels. A run whose line climbs back up more than 15 m, or that averages under 10 % with 20 m over 40 %, keeps its numbers with a warning and is left out of the ranking by steepness.
• Where the relief does not reach part of a line there is no altitude: the page says so, and the drop and the average count only what is measured.
• The relief is the ground, not the snow: the cover, the grooming and the moguls of a given day change what a skier finds.
• These pages are not for navigation or safety, and they do not say what is open: ask the ski area.

Why other numbers differ

Published figures for one run often disagree. Some give the steepest few metres, others an average; some are in degrees, others in per cent (45° is 100 %, 37° is 75 %); some measure along the slope, or another line. Where we have checked them, a run’s page lists them with their source and the day we read them.

Credits

• OpenStreetMap: © OpenStreetMap contributors — Open Database License (ODbL) 1.0
• IGN — LiDAR HD, BD TOPO®: © IGN – LiDAR HD · © IGN – BD TOPO® — Licence Ouverte / Open Licence Etalab 2.0
• swisstopo — swissALTI3D, swissSURFACE3D: © swisstopo — Open Government Data (free geodata of the Swiss Confederation)
• BEV — ALS DTM, ALS DSM 1 m: © BEV – Bundesamt für Eich- und Vermessungswesen, ALS DTM/DSM 1 m (15.09.2025) — CC BY 4.0
• Copernicus DEM GLO-30: © DLR e.V. 2010-2014 and © Airbus Defence and Space GmbH 2014-2018 provided under COPERNICUS by the European Union and ESA; all rights reserved — Copernicus DEM licence

Every source of the game and its licence

Report an error

If a number looks wrong, tell us which one and why: contact@geopeaks.com