How to Sync EPUB Files Across Devices — Cloud Storage Guide (2026)

June 12, 2026  ·  7 min read

Converting a PDF to EPUB is only the first step — getting that EPUB onto all your devices requires the right cloud storage setup. This guide covers the four major cloud storage services and which EPUB reading apps support each one.

Quick comparison

iCloud Drive — Apple ecosystem

iCloud Drive is the simplest option for users who read on iPhone, iPad, and Mac. Apple Books stores its library in iCloud automatically — any EPUB you add on one device appears on all others.

How to set up:

1. Ensure iCloud Drive is enabled: Settings → [Your Name] → iCloud → iCloud Drive → On.
2. Add an EPUB to Apple Books on any device — it syncs automatically.
3. Bookmarks, highlights, and reading position sync via iCloud as well.

Manual file access: You can also store EPUBs in iCloud Drive (not in Apple Books) and open them on demand from the Files app. This lets non-Apple apps like Chunky or Marvin access the files.

Limitations: iCloud sync works only on Apple devices. No Android or Windows native access without the iCloud for Windows app (which is cumbersome).

Google Drive — best for Android and cross-platform

Google Drive's 15 GB free tier and Android integration make it the best choice for Android users or anyone reading across Android, iOS, and desktop.

With Google Play Books:

1. Go to play.google.com/books in a browser.
2. Click the upload icon and select your EPUB files.
3. They appear in your Play Books library on Android, iOS, and web.

Google Play Books stores EPUBs in your Google account — they're technically in Google's servers, not a Drive folder, but the 15 GB quota applies.

With Moon+ Reader on Android:

1. Install Moon+ Reader and enable Google Drive access in Settings → Cloud Services.
2. Store your EPUB files in a Google Drive folder.
3. Moon+ syncs reading position and bookmarks via Google Drive.

With any reader on desktop: Download the Google Drive desktop app and store EPUBs in a Drive folder. Use Calibre, Thorium, or any reader to open files directly from the synced folder.

Dropbox — most universal app support

Dropbox has the broadest integration with third-party EPUB reading apps, especially on iOS. Marvin 3, Kybook 3, and several other iOS EPUB readers can sync directly with a Dropbox folder.

iOS workflow with Marvin:

1. Install Marvin 3 and connect your Dropbox account in Settings.
2. Place EPUB files in the designated Dropbox folder (e.g., /Dropbox/Books/).
3. Marvin syncs automatically and shows new books in the library.

Cross-platform workflow: Store EPUBs in Dropbox on your computer. On mobile, use an app with Dropbox integration (Marvin on iOS, FBReader or Moon+ on Android) to read from the same folder.

Limitations: The free tier is only 2 GB — enough for hundreds of EPUBs (typical EPUB is 1–5 MB) but limited if you store large files alongside them.

OneDrive — Windows and Microsoft 365 users

OneDrive is pre-installed on Windows 10 and 11. If you read primarily on Windows desktop and have a Microsoft 365 subscription (which includes 1 TB OneDrive storage), it's a natural choice.

Windows workflow:

1. Store EPUBs in your OneDrive folder.
2. Open with Thorium Reader, Calibre, or Freda (a Windows Store EPUB reader with OneDrive integration).
3. On mobile, open the OneDrive app and use "Open in" to send EPUBs to a reading app.

Limitations: Fewer reading apps have native OneDrive integration compared to Dropbox or Google Drive. Most workflows involve manually downloading files from OneDrive and opening them in a reader.

Converting and syncing in one workflow

A practical workflow for getting PDFs onto all your devices as EPUBs:

1. Convert the PDF to EPUB at toolkit.bot — free, 30 seconds, no account needed.
2. Download the EPUB file to your computer.
3. Copy it into your cloud storage folder (iCloud Drive, Google Drive, Dropbox, or OneDrive).
4. Open it on your phone or tablet using the reading app of your choice.

FAQ

Does Apple Books sync reading position across devices?

Yes — Apple Books syncs reading position, bookmarks, and highlights across all devices signed into the same Apple ID via iCloud, including iPhone, iPad, and Mac.

Can I use Google Drive with an iPhone EPUB reader?

Yes. Apps like Kybook 3 and Voice Dream Reader support Google Drive on iOS. You can also use the Google Drive iOS app to open EPUBs directly in Apple Books via the "Open In" share sheet.

What cloud service works best for large EPUB libraries?

Google Drive (15 GB free) or a paid plan. Dropbox's 2 GB free tier fills up quickly if you have hundreds of books. Google One plans start at $1.99/month for 100 GB.

Can I sync Calibre's library to the cloud?

Yes. Point Calibre's library folder to a synced location (Dropbox, OneDrive, or Google Drive on desktop). Note: don't open Calibre from two devices simultaneously against the same library folder, as this can corrupt the database.