How much fits on a flash drive

Every capacity in one table

Counted with a phone photo at 4 MB, a minute of 4K phone video at 350 MB and a song at 8 MB. Burst photos, RAW files and high frame rate video take much more. Documents and spreadsheets take far less, often under 1 MB each.

Why a 128GB drive shows 119GB

Makers count a gigabyte as a billion bytes; Windows counts it as 1,073,741,824 bytes and still calls it GB. The same drive therefore reads about 7% smaller on screen, and the file system takes a little more. Nothing is missing.

The 4GB file limit

Many drives arrive formatted FAT32, the format almost every car stereo, TV and camera can read. FAT32 cannot hold a single file over 4 GB, so a long 4K video or a disc image will not copy. Reformatting to exFAT removes the limit: Windows and Mac both read and write exFAT, and a Mac offers ExFAT for any drive over 32GB.

Reformatting erases the drive. Copy anything on it somewhere else first.

Picking a size

For school and office files, 32GB to 64GB is plenty. For phone photo backups, 128GB to 256GB covers a year or two of an average phone. For video work and whole-computer copies, start at 512GB, and look at the read speed as closely as the capacity: a 1TB drive at 100 MB/s takes almost three hours to fill.