Actual Usable Storage Calculator
Pick your advertised capacity and platform, then see what is really left for photos, videos and downloads. The decimal-versus-binary labelling gap costs you nothing, so it sits on its own line here instead of being subtracted. The operating system and preinstalled apps are what genuinely take the space, and whatever survives them is converted into photos and minutes of 4K video.
Actual Usable Storage Calculator
Your phone
Phone makers sell 1 TB as 1,000 GB and 2 TB as 2,000 GB, so those chips set 1000 and 2000. Type any other size directly.
Apple Intelligence reserves about 7 GB for its on-device models.
What is already on it
Prefilled from the platform above, and editable. Settings, then General, then iPhone Storage, or Settings, then Storage on Android, shows this as System, iOS or System Data.
Your own apps, not the preinstalled ones. A typical loadout of social apps is 10 to 20 GB, and one big 3D game can be 10 GB on its own.
iOS 26 and preinstalled apps 14 GB, System Data 7 GB, Apple Intelligence 7 GB.
What that free space holds
12 MP HEIC at 2.5 MB a photo, 4K at 30 fps at 170 MB a minute, both Apple's own in-device figures.
The binary number, for reference only
Not missing, just a different unit. This is what Windows Explorer or an iOS 10-era device would show, and it is never subtracted above.
Swipe44
Photo Cleaner
The recoverable gigabytes are in your camera roll
You cannot get the system partition back, but the camera roll is yours to clear. Swipe44 goes one photo at a time: right to keep, left to delete, one batch.
Free · No sign-up needed
Where your missing gigabytes actually go
Two things stand between the number on the box and the number in your storage bar, and they are not the same kind of thing at all. One is a labelling difference that costs you nothing. The other is real, permanent bytes.
- The labelling gap (costs zero bytes). Storage is sold in decimal gigabytes, 1 GB being 1,000,000,000 bytes. Some software counts in binary gibibytes instead, 1 GiB being 1,073,741,824 bytes. Convert one to the other and the figure shrinks by 6.9%, but not a single byte has gone anywhere. On a modern phone this conversion is not even applied, so it never touches what Settings reports.
- The OS footprint (costs real bytes). The operating system, the system partition, System Data and the preinstalled apps you cannot uninstall occupy actual space. This is the row your phone labels System, iOS or System Data, and it is where essentially all of the missing capacity on a current phone has gone.
A small firmware reserve accounts for a little more, roughly 0.3%, which is why a 256 GB iPhone reports 255 GB rather than a round 256. Here is the whole chain per tier, using an iPhone with Apple Intelligence on (28 GB) and 20 GB of installed apps:
| Advertised | Settings total | After the OS | After typical apps |
|---|---|---|---|
| 64 GB | 63.8 GB | 35.8 GB | 15.8 GB |
| 128 GB | 127.6 GB | 99.6 GB | 79.6 GB |
| 256 GB | 255.2 GB | 227.2 GB | 207.2 GB |
| 512 GB | 510.5 GB | 482.5 GB | 462.5 GB |
| 1 TB (1,000 GB) | 997.0 GB | 969.0 GB | 949.0 GB |
| 2 TB (2,000 GB) | 1,994.0 GB | 1,966.0 GB | 1,946.0 GB |
Notice how the OS footprint is close to fixed while the capacity multiplies. It costs a 64 GB phone 44% of its space and a 1 TB phone about 3%. That is where your gigabytes went, and the arithmetic has nothing to do with it. If you are still choosing a tier, the iPhone Storage Size Calculator runs the same figures against how much you actually shoot.
The 119GB myth: what your phone's Settings really shows
Search for this and you will be told a 128 GB phone "formats to 119 GB". It is the most repeated claim in the category and, for a phone bought in the last several years, it is wrong. Both platforms moved to decimal reporting years ago:
- iOS. Apple's support note on how storage capacity is measured names the binary system as the one used by "some apps and operating systems, such as iOS 10 and earlier and OS X Leopard and earlier". Apple is placing current iOS outside that group. Reports from modern devices match: a 256 GB iPhone shows 255 GB, a decimal readout minus the firmware reserve, not the 238 GB a binary conversion would produce.
- Android. The
Formatter.formatFileSize()API reference states that as of Android O (8.0), "the prefixes are used in their standard meanings in the SI system, so kB = 1000 bytes, MB = 1,000,000 bytes", and that powers of 1024 were used in Android N and earlier.
The binary number is not fictional, it is just measured somewhere else. It is still exactly
what you see in Windows Explorer (which prints "GB" while counting gibibytes), in
df output on a Mac or Linux box, and on a memory card or USB stick plugged into
a PC. That last case is the one people meet most often, and the
SD Card Storage Calculator covers it, because
a card really does read smaller than its label once a computer formats and reports it.
The arithmetic, if you want it: advertised GB × 109 ÷ 230 = GiB, a factor of 0.9313.
| Advertised (decimal GB) | Same capacity in GiB | Labelling gap |
|---|---|---|
| 64 GB | 59.6 GiB | 4.4 GB |
| 128 GB | 119.2 GiB | 8.8 GB |
| 256 GB | 238.4 GiB | 17.6 GB |
| 512 GB | 476.8 GiB | 35.2 GB |
| 1,000 GB | 931.3 GiB | 68.7 GB |
| 2,000 GB | 1,862.6 GiB | 137.4 GB |
Read that table as a translation, not a deduction. Subtracting it from your phone's capacity on top of the OS footprint double counts a loss that never happened, and overstates the damage by nearly 9 GB on a 128 GB phone.
What iOS and Android actually reserve, platform by platform
iPhone, iOS 26. About 14 GB for the operating system and its preinstalled apps, with reports clustering between 12 and 15 GB. System Data adds another 5 to 10 GB: caches, logs, Siri assets and staged updates. Apple Intelligence, if it is switched on, reserves roughly 7 GB more for its on-device models. That puts a realistic figure at 21 GB with Apple Intelligence off and 28 GB with it on, and heavier users see it drift into the mid thirties.
Android. Wider spread, because the maker decides how much ships on top of Android itself. A Pixel or near-stock build runs system files of roughly 10 to 15 GB, closer to 20 GB once the Google apps you cannot remove are counted, and owners of 128 GB Pixels commonly report around 90 GB usable. Samsung One UI is heavier at 25 to 27 GB, occasionally more on the largest models. Android also keeps the previous system image after an update, so the figure climbs over a phone's life. The Android "Other" Storage Calculator digs into what has piled up under that heading.
Read your own number rather than trusting a preset: Settings, then General, then iPhone Storage on iOS, or Settings, then Storage, then the System row on Android. Type it into the field above and the calculator will use yours instead.
The free space you have left is mostly photos
Once the OS and your apps have taken their cut, whatever is left will mostly fill up with camera roll. At Apple's own in-device figures, a 12 MP HEIC photo is about 2.5 MB and a minute of 4K at 30 fps is about 170 MB. So the 79.6 GB left on a typical 128 GB iPhone is roughly 31,800 photos, or about 7 hours 48 minutes of 4K. It sounds like plenty right up until the first long holiday.
The system partition is not coming back, and neither are most preinstalled apps. The camera roll is a different story: duplicates, near-identical burst frames, screenshots of things you dealt with months ago and videos you have never rewatched are usually the largest genuinely recoverable block on the phone.
That is the job Swipe44 does. You go through the roll by swiping, right to keep and left to delete, working from Recents, Random or one month at a time. Duplicates are hashed on the device and grouped for review. Everything you mark collects in a pending pile, and the whole batch goes at once behind a single system confirmation, with a tally of the space you got back. Nothing is uploaded, and iCloud originals are never downloaded.
To turn the number above into an order of work, the Phone Storage Planner ranks what to clear first by how many gigabytes it returns for the effort.
Frequently Asked Questions
Common questions about actual usable storage calculator
Why doesn't my 128GB phone have 128GB of free space?
Two separate things get blamed, and only one of them is real. The first is unit labelling: storage is sold in decimal gigabytes (1 GB = 1,000,000,000 bytes) while some software counts in binary gibibytes (1 GiB = 1,073,741,824 bytes). That difference costs you zero bytes, and on a modern phone it does not even show up, because iOS 11 and later and Android 8 and later both report decimal. The second is the operating system and its preinstalled apps, and that one costs you actual, unrecoverable bytes. On a 128 GB iPhone, Settings reports about 127.6 GB total (a small firmware reserve accounts for the rest), and iOS plus System Data plus Apple Intelligence take roughly 28 GB of it before you install anything of your own.
Does a 128GB iPhone really show only 119GB in Settings?
No. Apple's support note on how storage capacity is measured lists the binary system as the one used by "some apps and operating systems, such as iOS 10 and earlier and OS X Leopard and earlier", which is Apple saying current iOS is not in that group. A 128 GB iPhone running iOS 11 or later reports roughly 128 GB as its total, not 119 GB. The 119.2 figure is what Windows Explorer, an iOS 10-era device or a hard-drive conversion tool would show for the same physical chip. Same bytes, different ruler.
What is the difference between GB and GiB?
A gigabyte in the decimal (SI) sense is 1,000,000,000 bytes. A gibibyte is 2 to the power of 30, or 1,073,741,824 bytes. The ratio is 0.9313, so any capacity expressed in GiB reads about 6.9% smaller than the same capacity in GB. Nothing is lost in the conversion, it is one quantity written on two different scales. You still meet GiB in Windows Explorer (which calls them GB but counts them as GiB), in SD cards and USB sticks read on a PC, in "df" and "du" output on macOS and Linux, and on phones old enough to run iOS 10 or Android 7.
How much storage does iOS take up on an iPhone?
Around 21 to 28 GB on iOS 26. Budget about 14 GB for the operating system and its preinstalled apps, 5 to 10 GB for System Data (caches, logs, Siri assets, update staging), and about 7 GB more if Apple Intelligence is switched on. Settings, then General, then iPhone Storage shows your actual figure at the bottom of the bar. If you are deciding which capacity to buy rather than auditing one you own, the iPhone Storage Size Calculator works the question from the other end.
How much storage does the Android system use?
Between 15 and 30 GB depending on who made the phone. A stock or Pixel build runs nearer 20 GB once the undeletable Google apps are counted, with system files alone around 10 to 15 GB. Samsung One UI is heavier, typically 25 to 27 GB, because of the extra Samsung and Google preinstalls shipped alongside it. The number also creeps upward over a phone's life, since Android holds on to the previous system image after an update and app caches accumulate under "System". The Android "Other" Storage Calculator breaks down what has collected in that category.
How much of a 256GB phone can I actually use?
Settings reports about 255 GB as the total. On an iPhone with Apple Intelligence on, roughly 227 GB is left after iOS takes its share, and about 202 GB once a typical 25 GB of your own apps is installed, which is around 79% of the number on the box. A Samsung at the same capacity with the same app loadout lands near 203 GB. Four fifths of the advertised figure is a fair rule of thumb across both platforms.
Why does my phone show less free space than this calculator says?
The gap is almost always System Data, which drifts rather than sitting still. Cached streaming video, Messages attachments and their thumbnails, an app's own cache, staged OS updates and the Recently Deleted album all live there. Recently Deleted is the one that catches people out: photos stay in it for 30 days and keep occupying space the whole time. Empty it, then re-read the storage bar before assuming the calculator is wrong.
Can I get any of the OS storage back?
Not the system partition itself, and not the preinstalled apps on most phones. What you can reclaim is System Data caches, leftovers from offloaded apps and, biggest by a wide margin, the camera roll: duplicates, near-identical burst frames, screenshots you dealt with months ago. That is the part Swipe44 is built for, and the Phone Storage Planner ranks what to clear first.