How GPS Works Without Internet — A Complete Guide

Open Google Maps underground. You see "No Connection" and assume GPS is broken. Try Apple Maps in a foreign country with roaming off — nothing loads. Most people conclude the same thing: GPS needs internet.

They're wrong. GPS has never needed internet, and it never will. The confusion comes from how apps work, not how GPS works. In this guide, we'll separate the two and explain exactly what happens when your phone finds you on a map — and what happens when it can't.

What GPS Actually Is

GPS stands for Global Positioning System. It's a constellation of satellites operated by the United States Space Force that broadcasts positioning signals worldwide. According to GPS.gov, the U.S. government commits to maintaining at least 24 operational GPS satellites at all times, and has consistently flown 31 for over a decade.

These satellites orbit at roughly 20,200 kilometers above Earth in six orbital planes, completing two full orbits every day. Each one carries multiple atomic clocks accurate to within nanoseconds and continuously broadcasts two things: its exact position in space and the precise time.

That's it. The satellites don't know you exist. They don't receive anything from your phone. They simply shout their position and time into the void, and any receiver on Earth can listen.

How Your Phone Calculates Position

Your iPhone (and every smartphone since roughly 2008) contains a GPS receiver chip. This chip does one thing: it listens to satellite signals and measures how long each signal takes to arrive.

Since radio waves travel at the speed of light (approximately 299,792 km/s), the chip can calculate the distance to each satellite by multiplying the travel time by the speed of light. With the distance to one satellite, you know you're somewhere on a sphere around that satellite. With two, you're on the circle where two spheres intersect. With three, you narrow it to two points. With four, you can pinpoint your exact latitude, longitude, altitude, and correct for any clock error in your phone.

This entire process — receiving signals, measuring delays, calculating position — happens on your phone. No data is sent to any server. No internet connection is involved. The GPS chip is a passive receiver, like a radio that only listens.

GPS vs. Cell Towers vs. Wi-Fi: Three Different Systems

Here's where the confusion starts. Your phone uses three separate systems to determine location, and most apps blend all three without telling you which one is working:

GPS (Satellite Positioning)

Receives signals from orbiting satellites. Works anywhere with a clear view of the sky — mountains, oceans, deserts, airplanes. Accuracy: 3-5 meters outdoors. No internet, no cell signal, no Wi-Fi required. The only limitation is it needs sky visibility, so it degrades indoors, underground, and in dense urban canyons.

Cell Tower Triangulation

Estimates your position based on which cell towers your phone can see and how strong each signal is. Accuracy: 100-300 meters (sometimes worse in rural areas, better in dense urban areas). Requires an active cellular connection. Completely useless without cell service.

Wi-Fi Positioning

Apple and Google maintain databases mapping Wi-Fi network names to physical locations. When your phone sees known Wi-Fi networks, it can estimate your position. Accuracy: 15-40 meters in urban areas. Requires Wi-Fi radio to be on (not necessarily connected). Only works where Wi-Fi networks have been previously mapped.

Assisted GPS (A-GPS)

This is the bridge between GPS and internet, and the source of most confusion. When your phone has internet, it can download satellite orbit data (called almanac and ephemeris data) from Apple or Google servers. This tells your GPS chip roughly where to look for satellites, reducing the time to first fix from 30+ seconds to 2-5 seconds.

Important: A-GPS only speeds up the initial lock. Once your GPS chip has found satellites, it works entirely independently. If you lose internet mid-hike, your GPS continues working — it just might take longer to reacquire satellites if you restart the app.

Why Google Maps Fails Without Internet (But GPS Doesn't)

This is the key insight most people miss. When you open Google Maps or Apple Maps without internet, two things fail simultaneously:

1. Map tiles can't load — The visual map (streets, terrain, labels) is downloaded from servers in real time. Without internet, you see a blank screen or a cached sliver of the last area you viewed.
2. The app blames 'location' — Most map apps show a generic 'Location unavailable' or 'No connection' error, which makes users think GPS itself has failed. In reality, the app can't display your position because it has no map to show it on.

Your phone likely knows exactly where you are via GPS. But the app has no way to show you, because the map — the visual layer — requires internet. It's like knowing your exact grid coordinates but having no paper map to plot them on.

Five GPS Myths Debunked

Myth 1: "GPS uses mobile data"

GPS itself uses zero data. It's a receive-only signal from satellites. However, apps that use GPS (like Google Maps) consume data to download maps, calculate routes, and display business listings. The GPS positioning itself is free and uses no data whatsoever.

Myth 2: "GPS doesn't work in airplane mode"

Airplane mode disables your cellular radio, Wi-Fi, and Bluetooth transmitters. GPS is a passive receiver — it doesn't transmit anything. On most iPhones, GPS continues to receive satellite signals in airplane mode because there's nothing to interfere with aircraft systems.

Myth 3: "You need cell towers for GPS"

GPS and cellular are completely independent systems. GPS uses satellites at 20,200 km altitude. Cell towers are ground-based infrastructure. They're as related as FM radio and television — both use radio waves, but they're entirely separate networks.

Myth 4: "GPS only works outdoors"

GPS works best outdoors, but it often works indoors too — just with reduced accuracy. Near windows, in cars, in tents, and in lightweight structures, GPS signals often penetrate enough for a usable fix. Concrete, metal, and underground locations block signals almost entirely.

Myth 5: "GPS is owned by phone companies"

GPS is owned and operated by the United States government and is freely available to anyone on Earth with a GPS receiver. No subscription, no account, no payment. It's a public utility funded by U.S. taxpayers. Similar systems exist from Europe (Galileo), Russia (GLONASS), and China (BeiDou).

GPS Accuracy: What to Realistically Expect

According to GPS.gov, GPS-enabled smartphones are typically accurate to within about 4.9 meters under open sky. But accuracy varies dramatically by environment:

• ▶Open sky (fields, water, mountain tops) — 3-5 meters. This is ideal GPS territory with maximum satellite visibility.
• ▶Suburban areas — 5-10 meters. Some buildings may partially block signals.
• ▶Dense forest — 10-20 meters. Tree canopy absorbs and scatters GPS signals, particularly when wet.
• ▶Urban canyons (tall buildings) — 15-50 meters. Signals bounce off buildings (multipath effect), confusing the receiver.
• ▶Indoors near windows — 10-30 meters when it works. Signals are very weak through building materials.
• ▶Underground, deep indoors — No fix. GPS signals cannot penetrate rock, concrete parking structures, or subway tunnels.

Modern iPhones also use GLONASS, Galileo, and BeiDou satellites in addition to GPS, which increases the total number of visible satellites and improves accuracy in challenging environments.

How SkyLocation Uses Pure Satellite Positioning

Most location apps are designed for connected scenarios — they need internet to be useful. SkyLocation is designed for the opposite: it assumes you have no connection and gives you the raw GPS data your phone is already computing.

When you open SkyLocation, it reads the position directly from your iPhone's GNSS (Global Navigation Satellite System) chip, which processes signals from GPS, GLONASS, Galileo, and BeiDou simultaneously. It displays:

• ▶Latitude and longitude — Your exact position on Earth
• ▶Altitude — Height above sea level (GPS-derived)
• ▶Speed — Your current ground speed
• ▶Accuracy — The current horizontal accuracy of your fix in meters
• ▶Reverse geocoding — Country and approximate region (when available)

No map tiles are downloaded. No data is sent to servers. No account is needed. The entire computation happens on your device, which is why it works identically whether you're in downtown Tokyo or 200 miles offshore.

People Also Ask

Does GPS use battery?

Yes, but less than cellular radio. The GPS chip consumes about 25-40 mW of power, compared to 500+ mW for active cellular data. With airplane mode on and only GPS active, battery drain is minimal — many hikers report using SkyLocation for a full day with negligible battery impact.

Does GPS work at night?

Yes. GPS uses radio waves, not light. It works identically in complete darkness, in fog, in rain, and in storms. Weather has virtually no effect on GPS accuracy.

Why does Google Maps need internet if GPS doesn't?

Google Maps needs internet to download map imagery, calculate routes, show business listings, provide traffic data, and run search queries. These are all server-side features. The GPS position itself (the blue dot) is computed locally, but without a map to display it on, it's invisible to you. Apps like SkyLocation solve this by showing you the raw coordinates without needing a map.

See your GPS coordinates without internet — right now.