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Using GeoPDF Maps Offline on Your Phone

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A GeoPDF is an ordinary PDF map with coordinates built in, so a map app knows where every point on the sheet is on the ground. On your phone, that means a blue dot on the publisher’s own map, and it keeps working with no cell signal. Here is how to set it up so it works when you need it.

Why it works without signal

Your phone’s GPS receiver listens to satellites; it doesn’t need cell service or Wi-Fi to know where you are. What needs a connection is the map. A downloaded GeoPDF is stored on the phone, so the app can draw your position on it anywhere. The coordinates in the file do the rest: no internet lookups, no map tiles to fetch.

1. Install the map app

The Cartahaven map app runs in the browser at app.cartahaven.com and installs to your home screen, where it opens like any other app, even offline.

  • iPhone or iPad: open app.cartahaven.com in Safari, tap Share, then “Add to Home Screen”.
  • Android: open app.cartahaven.com in Chrome and tap “Install” (or ⋮, then “Install app”).

On iPhone, maps saved in Safari and maps saved in the Home Screen app are kept apart. Install first, then do everything below from the Home Screen app.

2. Get the maps onto the phone

  • Maps from the store: on a map’s page, tap “Get this map (free)” or buy it, and it is saved to your account. In the app, sign in with the same account and tap “Get my maps” (it reads “My purchases” once you are signed in) to download what you own. Browse maps or find maps by park, forest or state.
  • Your own files: tap “Import” in the app and pick a PDF from your phone, up to 500 MB. A GeoPDF shows your position straight away; GeoTIFFs work too. A PDF or picture without coordinates can be placed by hand (see how to georeference a scanned map).

While you are online, the app also saves a background map, elevation and, in the US, public land boundaries for the area around each map, so those work offline as well. Satellite imagery can be downloaded for offline use with Cartahaven Plus ($9.99 a year); viewing it online is free.

3. Check it before you lose signal

  1. Turn on airplane mode at home and open each map. If it opens and you can zoom in, it is on the phone. (Your dot only shows when you are inside the map’s area.)
  2. Make sure every sheet of your route is downloaded, including the other side of a two-sided map.
  3. Charge the phone and bring a battery pack. GPS and a bright screen use power.
  4. Carry a paper map and a compass as a backup. A phone can break, get wet or go flat.

4. In the field

  • Accuracy: usually within a few meters in the open, worse in deep canyons, dense forest or next to cliffs. The app shows how sure the phone is. The map itself is only as accurate as its maker drew it.
  • Screen off: phones stop GPS for web apps when the screen is off or the app is in the background. While you record a track the app keeps the screen on, and “Keep screen on” in Tools does the same at other times. Dim the screen to save battery.
  • Walking off the edge: while the app follows your position, it opens the next map you have when you walk onto it.
  • Tracks and pins: record a track, long-press to drop a placemark, and export them as GPX, KML or GeoJSON later.

Deleting the Home Screen app or clearing the browser’s website data removes the maps from that phone. Store maps download again from “My purchases”; sign in with backup on, or export your tracks and placemarks first. More answers on the help page.