Duplicate Photo Space Calculator

Where duplicate photos actually come from

Nobody sits down and decides to keep two copies of the same picture. The copies show up on their own, from about half a dozen places that all look harmless at the time.

Bursts are the big one. Hold the shutter on an iPhone and it takes 10 full-resolution frames every second, all kept at full size, all hidden behind a single thumbnail in the Photos app. A five-second burst at a birthday party is 50 photos that look like one photo. Messaging apps are the next culprit. WhatsApp saves incoming images to your camera roll by default, Telegram and Instagram can do the same, and so every meme anyone ever sent you is now yours to store. After that it gets petty: AirDrop receives, an iCloud sync retry that left a second file behind, an edit saved next to its original, a re-import from an old phone or a laptop backup that quietly doubled a chunk of the library while you were doing something else.

So this calculator asks about your habits instead of asking you to count duplicates. You cannot count them, and that is the whole problem. Bursts collapse into one thumbnail. A re-compressed WhatsApp copy is a different file byte for byte, so nothing doing an exact match will call it a duplicate. But you do know how often you shoot bursts and whether your messaging apps save to the roll, and those two facts predict the rate better than any guess you could make by scrolling.

How we estimate your duplicate count

The model is small enough to just show you:

• A 10% baseline for everyone, covering re-saves, edits, AirDrop receives, sync retries and old-phone imports.
• A burst adder: 2% if you rarely shoot bursts, 6% if you sometimes do, 14% if you shoot them constantly.
• A messaging adder: 5% if WhatsApp, Telegram or Instagram save to your roll.
• The total is clamped between 5% and 40%, because neither extreme happens in real libraries.

The middle burst setting, with messaging switched on and off, brackets the one hard number anybody has published. Avast looked at roughly 3 billion photos across more than 6 million photo-cleaner users and found 16% of stored photos are duplicates, and that 22% of saved photos are either duplicates or low quality. Our "sometimes, no messaging" case lands on 16% exactly. The 14% burst adder sits at the bottom of the 10% to 20% range burst frames are thought to occupy in heavy shooters' libraries. We kept it low deliberately.

The worked default goes like this: 20,000 photos, bursts sometimes, messaging on, 3.5 MB per photo. That gives a 21% duplicate rate, so 4,200 redundant copies, and 4,200 photos at 3.5 MB is 14.4 GB of waste inside a 68.4 GB library. One thing worth saying about the count: it is redundant copies only. A group of three near-identical shots contributes two, not three, because you keep one of them. That is what keeps the gigabyte figure honest as space you could actually get back.

It is still an estimate. The only way to get your real number is a perceptual-hash scan of your own library.

What those duplicates cost you in the cloud

Here is what both providers charge in the US in 2026, with the yearly figure worked out as twelve monthly payments so the two lines compare like for like.

That per-GB rate in the last column is what the calculator bills your wasted gigabytes against. On the 200 GB iCloud+ plan you are paying about $0.18 a year per gigabyte, so 14.4 GB of duplicates costs you $2.58 a year, or $12.88 over five. That is small. We are not going to pretend otherwise.

The real money is in the tier drop. Get under 200 GB instead of paying for 2 TB and that is $84.00 a year, every year you stay there. Get under 50 GB instead of 200 GB and it is $24.00. Duplicates tend to be the cheapest gigabytes you own, emotionally speaking, which makes them the first thing to cut when you are sitting just over a boundary. If you want the whole bill rather than the duplicate slice of it, there is an iCloud storage cost calculator for that.

A caveat if you are on Google: that storage is shared across Photos, Drive and Gmail. The tier fit above counts your photos and nothing else, so it flatters you. Whatever Drive and Gmail are already using comes out of the same pool.

Getting the gigabytes back

Start with the Duplicates album in the Photos app on iOS 16 and later. It is free and it is already there. It will not find everything, though, because it matches exact files. Two burst frames taken a tenth of a second apart are not the same file. Neither is a photo that came back to you through WhatsApp at a different compression level. To your eyes and to your storage bill those are duplicates. To that album they are not.

Perceptual hashing closes the gap. Swipe44 works out a 64-bit difference hash for each photo on your device, which describes what the image looks like rather than what bytes are in it, then groups anything visually similar and points at the newest shot as the likely keeper. You swipe through the groups, right to keep and left to delete. Everything you mark sits in a pending pile you can go back through before anything happens, and then the whole batch goes at once behind a single system confirmation. The app tells you what you freed. It all happens on the phone. Nothing is uploaded, and iCloud originals are never downloaded.

If the storage number does not budge right after, check Recently Deleted. Photos sit there for 30 days on both iOS and Android, still taking up room. Annoying, but it is also the reason a mistake costs you nothing.