Question
File OdditiesSeptember 30, 2026Why won't a USB drive with free space take a file bigger than 4GB?
Details
The limit is the file-size field, not the drive
FAT32 reserves 4 bytes in each directory entry for a file's size, so the largest value is 2³²−1 = 4,294,967,295 bytes, or 4GB minus one byte. Total capacity doesn't matter: a 64GB stick with 50GB free still can't hold a single 5GB video or ISO image, and the copy fails with a "file too large" error.
Why FAT32 is still everywhere
Compatibility. FAT32 is old enough that TVs, car stereos, cameras and game consoles almost all read it, so plenty of drives ship formatted that way. Microsoft's file-system comparison lists the numbers: FAT32's maximum file size is 4 GiB, while exFAT and NTFS allow 2⁶⁴−1 bytes. exFAT stores file sizes in 8 bytes precisely to replace FAT32 on flash drives and cards.
How to fix it
Copy everything off the drive, then reformat it as exFAT, which Windows and macOS can both read and write, making it the usual pick for a drive that moves between machines. If it only lives on Windows, NTFS works too. Formatting erases the drive. On a Mac, Disk Utility's "MS-DOS (FAT)" option is FAT32 and keeps the 4GB cap. If an older device only understands FAT32, split or archive the big file into parts under 4GB.
Also Asked As
file too large for destination file system · FAT32 4GB limit · can't copy file larger than 4GB to USB · exFAT vs FAT32