Scale and map types
Choosing an Ordnance Survey map means balancing close-up detail against the amount of ground shown on one sheet. The two main walking series are Explorer at 1:25,000 and Landranger at 1:50,000, so the same distance occupies more space on an Explorer map. That extra space allows Explorer to show more detail around paths and fields. Knowing how the scales relate to real distances helps you select a map and estimate how far a route extends.
Explorer and Landranger
Explorer and Landranger maps cover different needs: Explorer provides a closer view for walking, while Landranger puts a wider area on each sheet. Their scales, cover colours and levels of detail make the distinction easy to recognise.
| Feature | Explorer | Landranger |
|---|---|---|
| Scale and cover | 1:25,000 scale; orange cover. | 1:50,000 scale; pink cover. |
| Mapped detail | The larger scale gives more room for local features, including field boundaries and smaller route details. | The smaller scale shows a broader area, with less space for fine local detail. |
| Rights of way | Shows rights of way alongside field boundaries, helping walkers distinguish routes through a closely mapped landscape. | Shows rights of way too, but the wider view can make closely spaced routes and local features less distinct. |
| Walking use | A usual choice for walking when route detail and the layout of fields matter. | Useful for following a longer journey across a wider area or seeing how towns, roads and landscape features relate. |
For detailed navigation on foot, an Explorer map is generally the better fit: its 1:25,000 scale and field-boundary detail make local route choices easier to interpret. Choose Landranger when a broader overview is more useful, such as planning a journey that crosses a larger region.
Understanding scale
Map scale compares a measured length on paper with the corresponding horizontal distance on the ground. At 1:25,000, one centimetre on the map represents 25,000 centimetres, or 250 metres, on the ground; at 1:50,000, one centimetre represents 500 metres. This means 4 cm at 1:25,000 and 2 cm at 1:50,000 each represent 1 km.
To estimate a route, measure its line with a ruler and convert using the map’s scale. For example, a route measuring 6.8 cm on an Explorer map is about 1.7 km on the ground: each centimetre represents 250 m. For a winding route, follow its bends in short sections with a ruler rather than measuring one straight line between its endpoints.
Explorer’s larger scale is useful when you need to assess a short walk or distinguish nearby route options. Landranger’s smaller scale is convenient for a longer journey where seeing a wider area at once matters more. For close-up walking detail choose 1:25,000; for a broader regional overview choose 1:50,000.
Symbols and contours
An OS map uses a printed key and contour lines to show features and the shape of the land. Reading these details together helps you distinguish mapped paths from other features and understand how the ground rises and falls. The legend explains the map’s symbols, while contour patterns represent changes in elevation. Check the map edition before interpreting either, since conventions and contour intervals can differ.
Reading the legend
Use the Ordnance Survey map legend to identify what the printed symbols mean rather than relying on appearance alone. These checks help you match the key to the map in front of you.
- Check whether the map is an Explorer or Landranger edition, then use the legend supplied for that map rather than assuming every edition uses identical conventions.
- Find the legend printed with the map or provided for its edition; keep it open as you examine features in the mapped area.
- Choose a visible mapped feature and compare its colour, line style and pattern with the examples shown in the key.
- Match the complete mark, not just one detail: a dashed line, for example, should be checked against the corresponding entry.
- On Explorer maps, footpaths are shown as green dashes; compare the mapped dashes with the footpath entry in the legend.
- If a mark is unclear, check the map type and the key again before deciding what the feature represents.
Checking the key is more reliable than guessing from a symbol’s shape or colour, especially when several marks appear close together. For accurate map reading, use the legend for the specific edition you are carrying.
Contour lines and steepness
Contour lines join points that are at the same height above sea level. The vertical difference between successive lines is the contour interval: it is 5 metres on Explorer maps and 10 metres on Landranger maps. Read that interval before interpreting the pattern, because the same number of lines represents different height changes on the two map types.
Spacing shows how quickly the ground changes height across the map. Where contour lines sit close together, the ground is steep; where they are farther apart, the slope is gentler. A short distance between lines means you gain or lose the interval’s height over less horizontal ground. Widely spaced lines indicate a more gradual change, though the map does not give an exact slope angle by spacing alone.
The curves also reveal the landform. Contours that bend into a V-shaped pattern in a valley generally point uphill, towards higher ground; on a ridge, the contour bends point downhill. A series of closed loops commonly marks a summit, with the higher ground inside the inner contours. Follow the pattern across several lines to distinguish a continuous ridge or valley from a single bend in the terrain.
For a practical reading, first confirm the map’s contour interval, then follow the spacing and shapes across the route: close lines flag steep ground, while broad gaps and the direction of contour bends show gentler slopes, ridges and valleys.
Grid references and bearings
Grid references identify a precise point, while a compass bearing gives a direction to travel between locations. Together, they help turn a route marked on an Ordnance Survey map into clear, usable instructions. The grid uses numbered eastings and northings, and a compass translates a mapped direction into a field direction. Practising both skills makes navigation less dependent on a phone signal or charged battery.
Six-figure grid references
A six-figure grid reference pinpoints a location within a 1 km grid square to an accuracy of about 100 metres. Read the eastings first, moving across, then the northings, moving up; each extra digit divides the square into tenths. Use this sequence to locate a point:
- Find the grid square containing the point, using the two-digit easting along the bottom and the two-digit northing up the side.
- Read the easting first: estimate how many tenths across the square the point lies, counting from its left-hand grid line.
- Read the northing next: estimate how many tenths up the square the point lies, counting from its bottom grid line.
- For example, a point four tenths across and six tenths up square 23, 41 has the six-figure reference 234416.
- Each added digit represents one tenth of a kilometre, or 100 metres, so the final pair narrows the location to a small area.
- Keep the order consistent: across before up. Reversing the easting and northing places the reference in a different square.
Practise on a clearly printed feature, such as a junction or building, and compare the digits with the map grid. The method gives a useful location without implying that every feature can be identified to an exact point on the ground.
Using a compass
A compass bearing is an angle measured clockwise from north. To take one from a map, connect your starting point and destination with the compass edge, then set and follow the direction shown by the compass.
- Place the compass flat on the map, with its straight edge joining your location to the destination and its direction-of-travel arrow pointing towards the destination.
- Turn the compass housing until its orienting lines run parallel to the map’s north-south grid lines, with the orienting arrow pointing towards the top of the map.
- Read the bearing in degrees at the index mark. Map bearings refer to grid north; check the map’s grid-magnetic information and adjust when needed.
- On the ground, hold the compass level and turn your body until the needle’s north end sits inside the orienting arrow, often called “red in the shed”.
- Follow the direction-of-travel arrow towards a visible landmark, then take the bearing again if the route requires a change of direction.
- Keep the compass away from metal objects and electronic devices while taking a reading, as nearby interference can affect the needle.
Carry a paper map and compass even when using a phone app: cold weather can drain a phone battery quickly, while these tools need no power. A grid reference and a bearing provide a practical way to locate points and navigate without relying solely on a phone.
Putting map-reading skills together
A map becomes more useful when its scale, symbols, contours and grid are read as parts of the same picture. Before walking, use them to relate the distance between points to the features and terrain shown on the sheet. While moving, compare what is visible with the mapped pattern rather than relying on one clue alone. Repeating this process links preparation with position checks on the ground.
Combining map-reading skills
Prepare to follow a walk by working through the map in a consistent order. Each step adds a different kind of information, from distance to terrain and position.
- Mark the start, finish and key turning points on the planned line, so you can see which sections need closer attention before setting out.
- Use the map scale to estimate distances between those points, then compare the total with the time available and the length of each leg.
- Check the Ordnance Survey map legend for mapped features along the line, such as roads, paths, buildings or watercourses that can help identify junctions.
- Read the contours around climbs and descents to understand how the ground rises or falls, and note where the shape of the land changes.
- Choose clear reference features near decision points, such as a road crossing or a stream junction, rather than relying only on a long stretch of path.
- Use the grid to identify the relevant map squares and record grid references for important points, keeping each coordinate beside its matching feature.
Bring the observations together: a distance estimate describes how far apart points are, while symbols and contours explain what lies between them. Grid references let you connect those details to specific locations on the map.
Checking your position as you walk
At a recognisable point, pause and compare the map with the view around you. Look for a combination of details, such as a path meeting a road, a stream bending near a slope, or a building beside a change in contour shape. Check that their order and direction match the map; a single feature may be difficult to identify, but several features in the same arrangement provide a clearer fix. When the surroundings match, confirm your position with the grid. Identify the square containing the feature, then read its eastings and northings to locate the point rather than estimating from memory. If the feature appears in a neighbouring square, recheck the map orientation and the feature pattern before continuing. Practise matching the map and ground during short walks, including recording a few grid references and checking them against recognisable features. Keeping a paper map available means the same checks can continue without relying solely on a phone or its battery.