Real numbers: how much of my Google Photos was already in OneDrive
56% of the photos and videos in my Google Photos download were already in my OneDrive: 40% as identical files, and 16% as the same photo saved a bit differently, confirmed by comparing the pictures. When I merged the rest, 3,856 files (59.5 GB) were copied in about 6 hours and every one was checked, while 9,691 weren't needed.
I'm David, and I'm building MergeMyLibrary, a tool that moves Google Photos into OneDrive without duplicates. I tested it on my own library first. This page has every number from that test, and how each one was counted. No photos, file names or places, just totals.
You're welcome to quote any number here. Please link to this page.
What was in my two clouds?
My phone (Android) had been backing up to both Google Photos and OneDrive for years, except for a few years when only OneDrive was backing it up.
| Google Photos (the copy Google gave me) | OneDrive | |
|---|---|---|
| Photos and videos | 13,547 different ones (13,828 files; identical files counted once) | 73,182 images and 5,581 videos |
| Size of the photos and videos | About 192 GB | About 239 GB (25 GB of images, 214 GB of videos) |
| Everything else | 180,738 other files (55 GB) |
So about 431 GB of photos and videos across the two.
How much of my Google Photos was already in OneDrive?
| What the app found | Photos and videos | Share | Size |
|---|---|---|---|
| The identical file was already in OneDrive | 5,450 | 40% | 127.3 GB |
| The same photo was already in OneDrive, saved a bit differently (confirmed by comparing the pictures) | 2,113 | 16% | 3.2 GB |
| Not sure: sent to me to decide | 575 | 4% | 0.7 GB |
| Only in Google | 5,409 | 40% | 60.6 GB |
| Total | 13,547 | 100% | About 192 GB |
56% was already in OneDrive. For me, that meant years of paying twice for the same photos.
- Already in OneDrive: 56% (40% identical, 16% the same photo saved differently)
- Not sure, so I decided: 4%
- Only in Google: 40%
How do you know two photos are the same?
Two ways, in this order:
- Identical files. OneDrive keeps a unique code for every file, worked out from its contents. My app works out the same code for each file in Google's copy. Same code means the very same file.
- The same photo, saved differently. Google sometimes changes a file (for example, shrinking a video), so the codes don't match. For these, the app looks for the same moment (allowing for time zones), then compares the pictures themselves. Photos taken a second apart, like bursts (several shots in quick succession), are different photos and are never treated as copies.
If the app still isn't sure, it asks. If you don't answer, it copies the photo, so nothing is lost.
How sure are you? (I checked 300 matches by eye)
| Check | Result |
|---|---|
| Identical files (100 pairs) | Right every time. The few I first marked "different" or "not sure" turned out to be my checking page's fault (for example, it compared videos at different moments), not the app's. |
| The same photo, saved differently: first 100 pairs | I agreed with 97. Of the other 3, two were videos the app had right: the same clips, which Google had shrunk (same length to within 0.05 seconds, a fifth of the size). One was a real mistake: an edited photo matched to its original. That rule is fixed: edited copies now count as separate photos. |
| The same photo, saved differently: final 100 pairs | 100 of 100 right. |
In all, I checked 300 pairs by hand across three rounds.
What did I have to decide myself?
The app sent me 575 pairs it wasn't sure about. I answered all of them in 29 minutes:
- 566 were the same photo
- 8 were different
- 1 I couldn't tell
Honestly, it wasn't pleasant. Too many questions, and most had an obvious answer. For example, of 272 pairs taken at the same moment in the same place, 270 were the same photo. But 2 weren't, and those 2 are why it asks. The next version will ask far fewer questions. I'll post the new number here.
What got copied?
| Result | |
|---|---|
| Copied into OneDrive | 3,856 photos and videos, 59.5 GB |
| Checked after copying | All 3,856, each against OneDrive's own code for the file |
| Dates written into the copy | 1,681 |
| Already had the right date inside, so nothing needed writing | 2,083 |
| No date anywhere, not even in Google's note | 35 |
| Copied exactly as they were, because the file was damaged or unusual (as designed: copied, not fixed) | 57 |
| Places written into the copy | 113 |
| Uploads that failed and were retried successfully | 3 |
| Not copied | 9,691 (see below) |
| Time | About 6 hours, 3 files at a time |
| Albums rebuilt in OneDrive | 6 of 7 (102 photos placed). One failed: I already had an album with that name, and OneDrive won't allow two. |
How 13,547 became 3,856
| Photos and videos | |
|---|---|
| In Google's copy | 13,547 |
| Minus: the identical file was already in OneDrive | -5,450 |
| Minus: the same photo was already in OneDrive | -2,113 |
| Minus: pairs I answered "same" | -566 |
| Minus: Google's edited copies that looked the same as the original (my choice to skip) | -1,444 |
| Minus: extra copies of the same shot that Google had saved twice | -118 |
| Copied into OneDrive | 3,856 |
The 9,691 not copied are everything in the "minus" rows.
Before the full merge: a test, a failure and an undo
- First try: 0 files copied. OneDrive refused every upload. 7 empty folders were cleaned up. Nothing was lost, because the app only adds.
- Second try: 100 of 100 files copied (3.3 GB), each checked. All 97 that had a date carried the right one inside the copy. OneDrive's own "date taken" agreed on 75 of the 77 it displayed.
- Then I pressed undo, on purpose. The 100 copies and the 90 folders the app had made went to the OneDrive recycle bin. The 3,665 items in my phone's own photo folder in OneDrive were untouched, and the item count went back to exactly what it was.
How messy was each cloud on its own?
| Where | What I found |
|---|---|
| Inside OneDrive | 88,622 exact duplicate files (7.6 GB), in 39,824 groups. Mostly small files from copied folders; the biggest were videos stored in two or three folders. |
| Inside Google: the same shot saved twice | 118 extra copies (143 MB). Only the largest of each was copied. |
| Inside Google's copy: album repeats | 281 (958 MB). Google puts a photo in again for every album it's in. |
| Inside Google: edited copies | 1,775, and 1,523 of them were from 2014 (Google+ "Auto Enhance"). 1,444 looked the same as their original, so I skipped them; 294 looked different and 37 couldn't be told, so those were copied. |
| Photos with no date at all | About 59,000 images in my OneDrive from 2025 and 2026 have no "date taken" (screenshots, downloads, saved pictures). |
| Places | Google knew the place for 34% of the items in its copy. OneDrive shows a place for 4,034 of my photos. |
Duplicates take up space you pay for. The ones inside OneDrive are what the tidy-up will deal with. It's coming next, after the merge.
What these numbers don't tell you
- This is one library. Mine. It's not an average, and yours will be different.
- My phone backed up to both clouds for years. If yours didn't, you'll probably have less overlap.
- Android phone, English-language Google download, October 2026. Things may differ for iPhones or other languages.
- My app probably missed some. Since the merge, I've found that OneDrive sometimes saves its own copy of a photo under a slightly different name (for example "photo 5.jpg" instead of "photo.jpg"), and my app didn't always spot those. So up to about 429 of the 3,856 it copied may already have been in my OneDrive (my estimate, not yet checked). I'm checking them now, fixing the app so it catches them, and I'll post the real number here.
After the private test, I plan to add totals from other libraries here, combined and anonymous, and only with each person's permission.
Questions people ask
How much of a Google Photos library is already in OneDrive?
In mine, 56%. I don't have other libraries yet. The free report will show you your own number before you pay for anything.
How many duplicates were in OneDrive?
88,622 exact duplicate files, taking up 7.6 GB, before Google's copy came anywhere near it.
How long did the merge take?
About 6 hours for 3,856 photos and videos (59.5 GB).
Changes to this page
- 7 October 2026: first published.