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How to read OS maps for trails

OS maps look complicated until you know what to look for. This guide teaches the bits that actually matter for planning UK trails and days out.

OS map types (the quick choice)

Explorer (1:25,000) More detail. Best for footpaths, terrain detail and tight planning.
Landranger (1:50,000) Wider area. Great for overview planning and linking places together.

If you’re new: use Explorer for walking/trails, Landranger for big-picture route planning.

Rights of way: the simple version

OS maps show rights of way, but they don’t guarantee what’s practical today. Use them for planning, then confirm access on the ground.

  • Footpath: for walking.
  • Bridleway: usually walking, horses, cycles.
  • Byway/other routes: may allow wider use, but restrictions can apply.

Don’t guess legality from vibes. Check restrictions and signage if you’re using routes with vehicle access.

Contours made easy

Contours are height lines. The closer they are, the steeper it is.

  • Close lines = steep climb/descent.
  • Wide spacing = gentle slope.
  • V-shapes often point uphill in valleys (useful for spotting gullies).

Planning tip: if you see tight contours + exposed ridges, check wind and visibility before committing.

Grid references (how to use them)

Grid references help you communicate a precise location. A common method is: find the grid square, then measure along and up.

  1. Find the two-letter grid square.
  2. Read along (eastings), then up (northings).
  3. More digits = more precision.

For meetups and safety, using a grid ref is often clearer than “near that tree on the left”.

Planning a safer day out

  • Start point: parking + easy return option.
  • Weather: wind, rain and daylight change everything.
  • Time: allow for slow terrain, breaks, and turn-back time.
  • Plan B: a shorter loop if conditions shift.
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