Reading a map: scale, contour lines, legend

Scale is a ratio. '1:25,000' means: everything in reality is 25,000 times bigger than on the map. One centimetre on the map therefore equals 25,000 centimetres outside, which is 250 metres. At 1:50,000 it is 500 metres per centimetre. The smaller the number after the colon, the more detail the map shows – but the smaller the area it covers.

Contour lines turn a flat sheet into a landscape. The height difference from one line to the next is called the contour interval and is stated in the legend. Often every fifth line is printed thicker and carries a height value; the numbers are usually written so that their top faces uphill. That tells you where the ground rises and where it falls.

The legend and the map margin also tell you when the map was made, which grid it uses and how path types, rock, forest and water are shown. These symbols are not the same everywhere – every country and publisher has its own habits. So a quick look at the legend is worth it with every new map.

Measure distances along the path, not as a straight line. A piece of string laid along the bends and then measured against a ruler shows the real length. Winding mountain paths are often much longer than the gap between start and finish suggests. On top of that, every metre uphill or downhill takes longer than on flat ground.

Read not just the paths but the terrain too. Two paths may look equally long on the map – one stays flat in the valley, the other crosses a dense bundle of contour lines. For safety in particular, contour lines are the most important information on the map, because they show where a short stretch leads through steep, possibly dangerous ground.

A common and risky thinking error: when the landscape does not match the map, you 'bend' it in your head until it somehow fits. Honest scepticism is better. If something does not fit, stop early and check again instead of walking on and hoping.

A map shows the state of things when it was made. Forest roads get built, paths are moved, bridges removed, forest is cut down or grows back. So look at the publication year and watch for closure signs and notices on the ground.

The map also shows no current conditions: no snow, no flooding, no fallen trees, no ice on the path. And small steps in the terrain that are lower than the contour interval can vanish between two contour lines. A spot that looks harmless can still contain a small rock step.

Digital maps in apps follow the same rules. But zooming in changes the scale, and some details only appear at certain zoom levels. If you can read paper maps, you also understand digital maps better.

Start where you know your way around: your town, a park or a forest you already know. Look on the map for things you know – a crossroads, a stream, a hill – and see how they are shown. That way you learn the map's language without getting lost.

A good game for families: someone points at a spot on the map and the others predict what it looks like there – steep or flat, forest or meadow, uphill or downhill. Then you go there and check. Over time, looking at contour lines, you will almost see the hills in front of you.

Practise measuring as well: estimate a distance on the map, measure it, and then walk it. That gives you a feel for how far 500 metres or a kilometre really is.

In many countries topographic maps are published by national mapping agencies. Hiking maps from private publishers often build on them and add marked trails, huts and route notes. Scales around 1:25,000 or 1:50,000 are common for hiking.

Maps are sensitive to rain and wind. A waterproof case or a plastic bag protects them, and a folded map with the current area on top is much easier to handle in the wind.

A map works without power or signal. It is also an excellent tool for talking with others about a trip – or for describing to rescuers exactly where you are.