How to read the slope angle map

What do the colours on the slope angle map mean?

Each colour is one slope angle class in degrees. There are six classes, and the colours start at 20°.

• 20–24° blue
• 25–29° light green
• 30–34° yellow
• 35–39° orange
• 40–44° red
• ≥45° magenta

The map does not give a slope angle for a single point. Compare the colours with the legend, which is always visible on the map. On the map the colours look lighter than in the legend, because the slope layer is partly transparent and the basemap shows through it.

Uncoloured terrain is either below 20° or a place where the source data has a gap. The map does not tell these apart, so uncoloured does not mean flat or safe.

Class limits are approximate. Slope angle is stored in 2° steps, so a slope of 25.0–25.9°, for example, still shows in the blue 20–24° class.

How steep is 30 degrees?

Degrees and percent are different scales. On a 30° slope, the height changes by about 58 metres over 100 metres of horizontal distance, so the slope is about 58%. The map colours start at 20°, which is about 36%; 45° is 100%. On the map, yellow is the 30–34° class. For other values, use the Slope calculator (in Finnish).

Reading the map step by step

1. Start with a wide view. The colours show at every zoom level. Zoomed out, each pixel shows the steepest value in the area it covers, so steep classes look larger than they do at close zoom. Zoom in when you look at a single slope.
2. Search for a place or open an area page. The map covers Finland, Sweden and mainland Norway. The place search finds official place names in all three countries: Finnish names from Maanmittauslaitos, Swedish names from Lantmäteriet's Topografi 50 map (fells, peaks, lakes, rivers, villages, protected areas and mountain stations) and Norwegian names from Kartverket. Use the local spelling, for example Ylläs or Tromsø. The search does not find addresses or coordinates. Eleven areas have their own page, among them Ylläs, Kilpisjärvi, Abisko and the Lyngen Alps. See all area pages.
3. Follow a possible line. Look at the colours along the line and in the terrain above and below it. The map does not draw or compare routes; you read the colours yourself.
4. Share the exact view. The Copy map link button copies a link whose #map= part stores the zoom level and the centre of the map. The link opens the same view for the person who receives it.

What does the slope angle map not show?

The map has no current information on snow, weather, wind, ice or trail conditions. It does not show which way a slope faces. The map does not recommend routes and does not navigate: the My location button centres the map on your position once, but the map shows no position marker and does not follow your movement. There is no offline mode.

The colours are computed from the elevation models of Maanmittauslaitos, Lantmäteriet and Kartverket on a 2 m grid. The grid size is the cell spacing of the raster, not the accuracy of a measurement: a single value does not describe the exact surface of a rock, a cliff, snow or vegetation.