Compass, GPS & Map Apps: What to Carry and How to Combine Them

Why carry more than a phone? Battery, cold, water and signal

A smartphone with a good map app is the most convenient navigation tool ever made: it shows your position as a dot on a map, follows a planned route and fits in a pocket. The problem is not what it does when it works, but how many ordinary things stop it from working. Four of them matter on almost every trip.

The practical answer is two independent systems, one of which needs no power: paper map and compass. The electronics become a fast second opinion rather than a single point of failure. Satellite positioning needs no mobile signal, only a view of the sky, so an offline map app works where an online one does not. The phone stays in the kit, but you can answer "what if this device is dead in an hour?" without hoping. The technique is in the navigation skills guide; this article covers the equipment.

Paper maps: scales, what they show and waterproof cases

A paper map has two strengths an app cannot match: it shows the whole area at a glance in a fixed, known scale, and it never needs charging. For walking and bushcraft the scale decides how much detail you get. The reading skills – contours, grid, symbols – are taught in map reading basics; here the focus is on which map to buy.

Which scale to buy

For navigating in forests, where features are small and close together, 1:25,000 is the best choice. Hiking maps from regional clubs or the national mapping agency are usually based on the same data, with marked trails added. A 1:50,000 map is a good second sheet for a long route and for seeing where the escape routes lie. Check the edition year: contours change slowly, but forest tracks, clearings and trail markings do not.

If you print your own map sections, print at 100 % and measure the scale bar with a ruler: a map shrunk to fit the page has a different scale than the one printed on it. Check the data licence too.

Waterproof map cases

Paper dies in the rain, so it needs protection. The usual options are a clear map case with a roll-top or zip, a map printed on waterproof paper, or a sturdy zip bag. The case should be big enough to show the route window without unfolding the whole sheet, and should have a cord so the wind cannot take it.

• Fold the map so that your route section is on top and you can scroll to the next section without opening the case.
• Write on the case, not the map: bearings, expected times and paces can be added with a pencil or a marker that wipes off.
• Keep it at hand: a lid pocket or a hip belt pocket is better than the bottom of the pack. A map you have to unpack in the rain is a map you will not read.
• Have a spare: a second copy of the key section in a zip bag, in a different place in the pack, covers loss and soaking.

Which compass for hiking? Baseplate, mirror, lensatic and button compasses compared

All compasses show magnetic north, but they differ in how well you can work with a map, how precisely you can aim and how much they weigh. The table compares the four types you will meet. The short answer to "what is the best compass for hiking": a baseplate compass (also called a map compass or orienteering compass) – it is made for exactly the combination of map and terrain that hikers use.

A compass in a watch, whistle, knife or phone is in the same category as a button compass: fine for a rough direction, not for a map bearing. Metal cases and electronics deflect the needle, and a phone sensor needs calibration and fails with the battery.

A sensible set-up

One good baseplate compass on a lanyard or in a chest pocket – not at the bottom of the pack – is enough for almost everything. A cheap spare on longer trips lets you cross-check a suspicious reading. Baseplate compasses typically weigh about 30–60 g.

Compass features that matter: declination, needle, scales, clinometer, luminous marks

Beyond the basic type, a few features separate a good compass from a merely adequate one. Most are useful, none is essential, and you should not pay for ones you will not use.

Declination adjustment

With an adjustable compass you set the local declination once, and the dial then gives map bearings without mental arithmetic – a real advantage, because adding when you should subtract is easy to miss. Check the setting before each trip and look up the current value; it changes slowly. By-hand correction is in the declination section.

Global needle

A needle is balanced for the slope of the earth's magnetic field in one region; elsewhere it can tilt and drag. A "global" needle works in all zones, which matters only if you travel far.

Romer scales and rulers

The ruler edges and the little corner scales, called romers, let you measure distance and read a grid reference to about 100 m without any other tools. Check that the scales match the map scales you actually use (1:25,000 and 1:50,000 are the common ones), and that the plate is long enough, around 10 cm, to draw a line between two points on the map.

Clinometer

A clinometer measures slope angle, handy for judging steepness. It is not a substitute for training: assessing snow slopes and avalanche terrain needs a proper course and rescue equipment, which this article does not teach.

Luminous markings

Glowing marks make a compass readable in the dark. Two principles exist in general terms: marks that store light and glow for a while afterwards, and marks with a permanent self-powered glow that lasts for years. The first kind need charging by light and fade during the night; the second kind do not. Either way, a headlamp in red mode is gentler on your eyes when you read the dial; see red light and night vision.

How to check a compass: bubble, polarity and interference

A compass can be wrong without looking wrong. Checking it takes five minutes and should be done at home, after buying, after a flight and whenever the compass has been near something magnetic. The four checks below are simple and need no tools.

Keep phones and knives away while you take a bearing

Anything with iron, steel or a magnet can pull the needle: a phone and its magnetic case, headphones, a pocket knife or fixed-blade knife, a steel belt buckle, trekking pole tips, a car, a fence or an overhead power line. The error comes without warning, and a few degrees is enough to put you far from your target after a kilometre. As a rule of thumb, hold the compass at arm's length from your body, with phone and knife in a pocket or on the other side of the body, and well away from vehicles and power lines.

Polarity reversal

Strong magnets – a speaker, a magnetic clasp on a bag or phone case, an electric motor – can reverse the magnetism of the needle, so that the "red" end points south. You then walk 180° in the wrong direction while everything on the compass looks perfectly normal. Store compasses away from such items, and if you suspect a reversal, replace the compass or have it checked, instead of trying to correct it in the field.

GPS vs phone for hiking: which is better?

Neither replaces a map and compass, and neither is the clear winner. A dedicated handheld GPS device is built for the outdoors; a smartphone is already in your pocket and does many other things. The right choice depends on the trip, and the typical figures below are rules of thumb that vary a lot between devices.

Which one should you carry?

For marked day trails a phone with offline maps and a power bank is usually enough, with paper map and compass in the pack. For multi-day, winter or remote trips a handheld GPS has real advantages: battery life, spare cells and controls that work with gloves. Many walkers carry both, with the phone in flight mode as emergency phone and backup map.

Satellite messengers and SOS devices

Beyond mobile coverage, there are devices that talk to satellites. In general terms there are three kinds: personal locator beacons, which send a distress signal with your position when activated; two-way satellite messengers, which also let you send and receive short messages and often include an SOS button; and smartphones with satellite emergency messaging, where available. They usually need registration, and some need a subscription. Learn how the SOS function works, test it where the manufacturer allows, and carry it where you can reach it with one hand.

Such a device is a safety net, not a navigation tool and not a reason to take bigger risks. It does not tell you the way, it only helps rescuers find you. How to signal for help, share your location and wait for rescue is covered in emergency signals and getting found; for Europe, the emergency number is 112.

Offline map apps: how to prepare maps, tracks and waypoints

An offline map app is only as good as your preparation. The work happens at home, on Wi-Fi, a day or two before you leave; once you are in the forest it is too late. Look for an app that shows a topographic map with contour lines, shows your position without mobile data, lets you download whole regions, imports and exports tracks and offers the coordinate format you need. Avoid apps that insist on a connection to show your position.

Saving tracks

A track is the sequence of positions your device records. It lets you retrace your steps, see where you left the route and compare plan and reality. Shorter recording intervals draw a finer line but use more power; choose a longer interval on multi-day trips. Export routes and tracks in a common track format so another device can open them if the first fails.

Do not follow a planned line blindly. Forest tracks change and apps assume the path exists; match what you see with the paper map, and trust the terrain over the screen.

Coordinate formats and map datum in general terms

The same point on earth can be written in several ways, and a device and a map can use different ones. Most apps let you switch the format; choose the one that matches your paper map and your emergency plan, and practise reading it aloud.

Two details prevent errors. First, the datum: the reference system the coordinates refer to. Your map states it in the margin, and most apps and devices use a global system by default; a mismatch can shift your position noticeably, so check the margin of the map. Second, always state the format and the hemisphere or zone when you read coordinates to someone else. In an emergency read them digit by digit and let the other person repeat them; the details are in how to share your location precisely. How the grid on a paper map works is explained in the grid references section.

Power management: power bank, cold batteries and flight mode

On a navigation trip, power is a resource like water: you plan it before you go (the power bank calculator helps) and ration it on the way. The goal is not to switch the phone off for good but to make the charge last until you really need it. Keep a reserve of about 20–30 % for an emergency call, as recommended in emergency signals and getting found.

Rules of thumb: you can use roughly 60–70 % of a power bank's printed capacity because of conversion losses, so plan with that. Charge at a break or in the evening, not at 5 %, and charge lithium-ion batteries only above freezing, as with headlamps. A battery that seems dead in the cold often works again after 10–20 minutes on the body.

Altimeter, barometer and watch features in brief

A barometric altimeter in a watch or GPS device converts air pressure into height. It is smoother than satellite altitude, but pressure also changes with the weather, so the reading drifts: recalibrate at a known height such as a map spot height or a hut. A steady pressure fall over several hours often signals changing weather; see reading the weather. A watch compass is a rough guide only. A plain watch is still useful for timing legs; see the hiking time calculator.

Practice drills: combine map, compass and app

Equipment you have never used in anger is a hope, not a system. These drills train the three tools together and show you where each one lets you down. Start on familiar ground in good weather, then add difficulty. Use the pace count calculator and the hiking time calculator to set the numbers.

Two more drills are worth adding. In the phone-off hour you navigate a known route with map and compass only. In the plausibility check you guess your position from slope, sun and terrain before you look at the app (see navigation without a compass). A short dusk leg with a headlamp in red mode trains reading the compass in poor light; see moving safely at night. Once you are comfortable, vary the conditions with the seasons: fog, rain and snow change what works – see the seasons guide for what each one demands. If you work from a camp, the same drills are a good use of an afternoon at a base camp: walk a loop on a bearing and return on the back bearing.

What to carry: navigation kit by trip type

The kit grows with the risk. A short walk on a signposted trail does not need what a winter trek does, but the principle stays the same: one system without power and one electronic system, plus a way to keep both dry and charged.

Weigh the pieces together: map, compass and pencil are well below a few hundred grams, a power bank is typically 150–300 g, a handheld GPS around 150–250 g. Put them in a lid pocket of the backpack so they are in reach, and add them to your bushcraft kit list or to the packing list from the Kit Builder. For the plan of the trip itself – turnaround times, escape routes and who knows where you are – see planning a bushcraft trip. If you stay out overnight, the rules in wild camping also apply.