Converters guide
MB to GB: why the drive is “smaller” than the box
A “500 GB” disk that shows 465 GB is doing two dictionaries at once. Marketing GB is 10⁹ bytes. Windows often shows GiB (1,024³). Neither side is lying. They refused to use the same word.
Updated 2026-09-19
Decimal on this MB→GB page
GB = MB ÷ 1,000 when both are SI. 1,000 MB is 1 GB. A 4,700 MB CD image is 4.7 GB.
If the OS says GiB, open the kibibyte / mebibyte pages or the SI vs IEC scaler. 1 GiB is about 1.074 GB.
What to tell a client
“The box used decimal. The computer used binary. Convert, then add headroom for the filesystem.” That sentence ends more tickets than a screenshot of Disk Utility.
Key takeaways
- This MB→GB tool divides by 1,000.
- GiB is 1,024³ bytes. Use the scaler when the OS disagrees with the sticker.
- Always leave spare space; live filesystems are not empty boxes.