Free practice tools
Practise map reading on real mountains.
Interactive tools built from real Ordnance Survey elevation data. Spin actual UK hills in 3D, read their contours and pin down grid references, right here in your browser. Free, no signup, and they work on your phone.
No signup, no download
Where do contour lines come from?
Drag the water level up a real mountain and watch every shoreline it leaves behind become a contour line. One slider, one idea, and contours suddenly make sense. Have a go.
Where contour lines come from
Flood the hill and watch the lines become shorelines
A contour line is just a shoreline. Every brown line on this map is the edge of the water you would get if you flooded the hill to that exact height — they are all sitting there waiting to happen. Flood it and watch the water land precisely on one line after another; drain it and watch each line reappear the moment the water falls past it.
Click through these — a simple cone, a twin top and three real hills all flood in completely different ways.
The hill
Drag to turn
The map
One line per 10 m of water
Water level
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above sea level
Lines above water
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Shoreline moved
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Loading…
One moment.
The bit that matters
Watch how far the shoreline travels each time the water goes up 10 metres. On gentle ground it sweeps a long way, so the lines sit far apart. On steep ground it barely moves, so the lines stack up almost on top of each other.
That is the whole trick. Lines close together mean steep. Lines far apart mean gentle. You are reading the shape of the ground from a flat piece of paper.
Elevation data: Ordnance Survey Terrain 50 via AWS Terrain Tiles. Contains OS data © Crown copyright and database right 2026, used under the Open Government Licence v3.0. The model is sampled at 50 m, so fine detail is generalised.
The free tools
Five more, free to use any time.
Each one drills a skill you’d otherwise only get to practise out on the hill. Bookmark them, come back before a walk, and see your answers get sharper.
Interactive Contour Lines Tool
See the map and the mountain as one thing. Spin a real 3D hill, run a section line across it, and watch the contours make sense.
Open the tool → 🏆Contour Lines Quiz
Can you match the ground to the map? Real landforms, four maps to choose from, and a score at the end so you know where you stand.
Take the quiz → 📍Grid Reference Practice
Read and give six-figure grid references on the real National Grid. It’s the skill that tells Mountain Rescue exactly where you are.
Start practising → 🛰️Grid Reference Finder
Press one button and your phone gives you your six-figure OS grid reference, ready to read down the phone to 999. No app, nothing sent anywhere.
Find my grid reference → ⏱️Walk Time Calculator
Tap Snowdon, Ben Nevis or Pen y Fan, or enter your own distance and ascent, and get your time with the corrections that make Naismith’s rule honest, plus when to leave.
Work out my walk →Prefer to learn before you play? The contour tool is also built into the guide: How to Read Contour Lines on an OS Map.
Inside the course
Seven more tools live inside the course.
Every module of the Mountain Navigation Course pairs its lessons with a practice tool. You learn the skill, then you drill it on a real mountain before you ever have to trust it on a real walk.
Steepness Reader
How long will your route really take? Read steepness straight from the contour spacing, then let Naismith’s rule show you what the climbing adds.
Sight a Bearing
Practise taking a bearing on the ground. Sight a summit on the skyline, read the dial, and check yourself against the right answer.
Take a Bearing
Lay a real compass on the map, turn the housing, line it up with the grid and read off your bearing. The full skill, done properly.
Back Bearings
The quick check that proves you’re still on your line. Turn around, take a back bearing, and catch a mistake before it costs you.
Relocation
Not sure where you are? Match the skyline in front of you to the map and work it out, the way instructors actually do it.
Slope Aspect
Which way does the ground fall away? Use the direction of the slope to pin down your position when everything looks the same.
Put a Bearing on the Map
Take bearings to what you can see, plot them on the map, and find yourself where the lines cross. Triangulation, made simple.
All seven come with the course, sitting right beside the lessons that teach them. Lifetime access, so they’re there the night before every walk you ever plan.
Start free
Not ready for the full course? Start free.
The free Digital Safety Net course is 13 short lessons that turn your phone into a proper backup safety tool. Instant access, and you’ll see exactly how we teach before spending a penny.
🧭 Not sure which course fits your level? Take the 2-minute Nav Skills Quiz
Quick questions
Before you dive in.
What’s the best way to practise map reading at home?
Little and often beats one big session. Ten minutes on an interactive tool like the contour quiz or grid reference practice builds the reading skills, and your next walk is where you test them for real. The tools on this page are free and run in your browser, so you can practise the night before every walk.
Are the navigation practice tools really free?
Yes. Everything on this page is free to use, with no signup and no card details. Seven more tools live inside the Mountain Navigation Course, one for each skill it teaches.
Do the tools work on a phone?
Yes. They run in your browser on phones, tablets and desktops, with nothing to download or install. On a phone the layouts adjust so the maps stay big enough to read.
Are the maps in the tools real OS maps?
The hills are real and so is the National Grid, but the maps are not Ordnance Survey map extracts. Each tool draws its own OS-style contour maps from Ordnance Survey’s open elevation data (OS Terrain 50), so what you practise on behaves like the real thing.