Formatting
FAT32, exFAT or NTFS: how to format a flash drive
A new drive that refuses a 5 GB video is not full: its FAT32 format caps a single file at 4 GiB. Pick the format your devices read, then reformat only after the files are copied off.
Why will a 5 GB file not copy to a new drive?
The copy stops partway or never starts, and Windows reports that the file is too large for the drive. Meanwhile the drive shows 100 GB free. Space is not the problem. Plenty of drives still ship formatted FAT32, an old file system that almost every car stereo and camera can read, and FAT32 refuses any single file larger than 4 GiB.
That limit is 4,294,967,296 bytes, which the box would call about 4.29 GB. At 350 MB a minute, it comes to roughly 12 minutes of 4K phone video in one file. A disc image, a long screen recording or a backup archive crosses the line just as easily. The cure is a different file system, and there are two candidates: exFAT and NTFS.
Both lift the cap. Microsoft lists the largest file on exFAT and on NTFS as 2 to the 64th power bytes, less one, a number near 18 billion billion bytes and far beyond any drive on our shelves. What separates the two is everything else that comes with the format, and which devices can read it.
FAT32, exFAT and NTFS side by side
FAT32 dates from the 1990s and remains the format nearly every device with a USB port understands. exFAT was designed for flash storage: it keeps the simple layout of FAT but drops the file size limit, and both Windows and macOS read and write it with no extra software. NTFS is the format Windows itself runs on. It adds file-level encryption, access control lists and journaling, a log of changes that helps a disk recover after a crash, and exFAT has none of those.
| File system | Largest single file | Windows | Mac | Typical car stereo or TV |
|---|---|---|---|---|
| FAT32 | 4 GiB | Reads and writes | Reads and writes, as MS-DOS (FAT) | Reads it: the safe pick |
| exFAT | 2 to the 64th power bytes, less one | Reads and writes | Reads and writes, as ExFAT | Newer models, see the manual |
| NTFS | 2 to the 64th power bytes, less one | Reads and writes | Reads only, without extra software | Some TVs, rarely a car stereo |
File size limits from Microsoft's file system comparison. Car stereos and TVs vary by model, and the manual lists the formats each one reads.
On a drive that travels between machines, the extras of NTFS count for less than one plain fact. A Mac opens an NTFS drive and copies files off it, but cannot save anything back to it. So a shared drive wants exFAT, and NTFS earns its place on a drive that only ever meets Windows computers.
Which format does each device read?
Start with the fussiest device the drive will meet, then make sure the rest can live with that choice.
- Windows PC: FAT32, exFAT and NTFS, reading and writing all three.
- Mac: FAT32 and exFAT for reading and writing. An NTFS drive opens and its files copy off, but nothing can be saved to it without extra software.
- Car stereo: FAT32 above all. Many units also expect a drive of 32GB or less and ignore anything bigger, so the manual is worth five minutes before you buy.
- TV: FAT32 nearly everywhere, with exFAT and NTFS on many newer sets. The manual names the formats for that model.
- Game console: exFAT or FAT32 for photos, music and video carried on a stick. A console that keeps games on an external drive formats that drive its own way first, which erases it.
- iPhone and iPad: the Files app opens drives formatted FAT32 or exFAT. A connected drive shows up under Browse by its own name, next to On My iPhone and iCloud Drive.
For most people the answer is exFAT. A Mac and a PC share it, phones and newer TVs read it, and it takes a file of any size. FAT32 stays the right choice for a small drive that lives in an older dashboard, where an 8 MB song never comes near the 4 GiB line. The flash drives for the car are sorted with that port in mind, and the 32GB drives sit right at the size many stereos accept.
A drive carries one format at a time. If the same stick goes to the car on Friday and to a Mac on Monday, FAT32 is the format both accept, and the price is the 4 GiB limit. Anyone who moves big video files as well will spend less effort on two drives than on reformatting one every week.
How do you reformat a drive on Windows?
Reformatting erases every file on the drive, so copy everything to your computer first and open a few of the copies to confirm they arrived whole. Then the job takes about a minute.
- Plug the drive in and open File Explorer.
- Right-click the drive in the left-hand pane and choose Format.
- In the window that opens, pick the file system: exFAT for a drive shared with a Mac, NTFS for a drive that only meets Windows, FAT32 for a small drive bound for a car or an older TV.
- Give the drive a name if you like, leave the other settings as they are, and start the format.
- Accept the warning that the data will be erased. On a new drive, a quick format finishes in seconds.
On most Windows versions the format window offers FAT32 only on drives up to 32GB. If a car stereo insists on FAT32, a 32GB drive is the simple way around that. Once the roughly 93% left after formatting is counted, it holds about 3,700 songs at 8 MB each. The full arithmetic for every size is on how much fits on a flash drive.
How do you reformat a drive on a Mac?
Disk Utility does the same job on a Mac. Apple names the Windows-friendly choices in its own terms: MS-DOS (FAT) for volumes of 32GB or less, and ExFAT for volumes over 32GB.
- Copy the files you want to keep, then plug the drive in.
- Open Disk Utility from the Utilities folder inside Applications.
- Select the drive in the sidebar.
- Click Erase, type a name, and set the format to MS-DOS (FAT) or ExFAT.
- Confirm the erase, then wait for the drive to reappear on the desktop under its new name.
Leave APFS and Mac OS Extended for drives that stay with Macs. Those are Apple's own formats, and Windows cannot open them without extra software. If your Mac has only USB-C ports, the drives for the Mac start with that plug.
What does reformatting erase?
Everything. A format writes a fresh, empty file system over the old one, and every file on the drive vanishes from view at that moment. Recovery tools can sometimes pull files back after a quick format, but nobody should count on it, and after a full format they are gone for good.
Reformatting does not change the room on the drive either. A 128GB drive shows about 119GB in Windows whichever of the three it carries, because the box counts a gigabyte as a billion bytes and Windows does not. Nor does formatting repair a failing drive: if files vanish or the drive keeps asking to be formatted, copy off what you can at once and retire it.
Every card at EasyFlash prints the capacity of each size, so before you buy you can see whether a drive sits under the 32GB line that FAT and many car stereos expect. Keep the copy you made before formatting, too. A flash drive is easy to lose, and the habits that protect what is on it are in our guide on keeping files safe.