Compass & altimeter apps — find north and altitude
A compass app reads your phone's built-in magnetometer to point at magnetic north — no internet, no sign-up, no tracking. An altimeter app pairs the barometer with GPS to tell you how high you are above sea level. Both work fully offline, which is exactly what you want on a trail with no signal.
Carbide bundles a compass and an altimeter into one all-in-one toolkit app, so you skip the ad-stuffed single-purpose downloads. Here is how each sensor works, how to calibrate for accuracy, and what to expect.
How a phone compass works (and why it needs no internet)
Your phone has a magnetometer — a tiny sensor that measures the Earth's magnetic field. A compass app reads that field, works out which way is magnetic north, and shows your heading in degrees. None of this needs a data connection or your location, so the compass runs the same in airplane mode on a mountain as it does at home.
That is also why it stays private: there is no lookup, no server call and no account. The heading is computed on the device from raw sensor values. A good compass shows the cardinal points (N, E, S, W) plus a numeric bearing from 0 to 359 degrees, so you can follow a precise direction rather than just a rough arrow.
Calibrate with the figure-8 motion
Magnetometers drift, especially near metal, magnets or speakers, so calibration matters. If the needle spins, lags or points obviously wrong, calibrate it: hold the phone flat and move it through a figure-8 pattern in the air a few times, rotating your wrist as you go. This sweeps the sensor through every orientation and resets its baseline.
- Move away from cars, laptops, desks with metal frames and phone cases with magnets.
- Draw a slow figure-8 in the air three or four times until the reading settles.
- Recheck against a known direction — sunrise is roughly east, sunset roughly west.
True north vs magnetic north
A magnetometer points at magnetic north, which is not the same as true north — the geographic top of the map. The gap between them is called declination, and it changes depending on where you are on Earth, from a fraction of a degree up to 20 degrees or more in some regions.
For everyday direction-finding, magnetic north is fine. For map and grid navigation you may want true north, which apps derive by adding your local declination. The compass shows magnetic heading; if you are plotting a course on a paper map, note your area's declination and adjust. For most walking, cycling and travel, the raw magnetic bearing gets you there.
Can I find qibla direction with a compass?
Yes — a compass gives you the bearing you need. Qibla is simply a direction in degrees from your location toward the Kaaba in Mecca, and a phone compass reads bearings in exactly those degrees. Look up the qibla bearing for your city (for example, it is roughly 118 degrees from Cairo), turn until the compass shows that number, and you are facing the qibla.
This is a manual method, not a dedicated qibla finder, so treat it as a practical aid rather than a religious ruling. Calibrate first with the figure-8 motion, keep the phone flat and away from metal, and cross-check the result — accuracy depends entirely on a clean magnetometer reading.
How your phone measures altitude
An altimeter app answers "how high am I?" using two sources. Many phones have a barometer that reads air pressure — pressure drops as you climb, so the app converts that pressure into an altitude. GPS gives a second, independent altitude estimate from satellites. The app can blend both for a steadier reading.
Barometric altitude is responsive and works indoors and offline, but it needs a sea-level pressure reference to be accurate, since weather shifts the baseline. GPS altitude does not need a reference but is noisier and needs sky view. Use unit conversions to switch between metres and feet with the unit converter when a trail sign and your app disagree on units.
Offline navigation for hiking and travel
The reason a phone compass and altimeter belong on a trip is that they keep working when the network does not. On a hike, in a remote village or on a flight, the compass still points north and the altimeter still reads your elevation, because both run on device sensors, not a data feed. That is the install-intent case: you want them already on your phone before you lose signal.
Because compass and altimeter depend on the magnetometer, barometer and GPS, a browser tab can't reach those sensors reliably — so these two live in the Carbide app rather than the web tools. The apps are coming soon for Android and iPhone. In the meantime you can check your device's sensor support with the web-based device info tool and see your rough location details with IP info.
Frequently asked questions
Does a compass app work without internet?
Yes. A compass reads your phone's magnetometer directly, so it needs no data connection, no GPS lock and no account. It works the same in airplane mode on a mountain as it does at home.
Does the app record my location or track me?
No. The compass heading is computed on your device from raw sensor values — there is no lookup and nothing is uploaded. The altimeter reads the barometer and GPS locally; your position and altitude stay on the phone.
How accurate is a phone compass and altimeter?
The compass is good to a few degrees once calibrated with the figure-8 motion and kept away from metal and magnets. Barometric altitude can be within a few metres with a correct sea-level reference, while GPS altitude is noisier — treat both as practical, not survey-grade.
Is the app free, and are there limits?
The compass and altimeter are free tools inside the all-in-one Carbide app, with no premium wall and no ads maze. The apps for Android and iPhone are coming soon.
How do I find my area's altitude above sea level?
Open the altimeter and let it settle — it reads your current elevation from the barometer and GPS. For a fixed reference figure, compare it against a known landmark or a trail sign, since local weather shifts the barometric baseline.
A phone compass and altimeter turn your device into an offline navigation kit — magnetic north in degrees, altitude above sea level, no internet needed. Both ship free in the all-in-one Carbide app, coming soon for Android and iPhone; until then, check your sensors with device info.