400 MB to GB
400 megabytes to gigabytes
Decimal (SI) — what most people mean
400 MB = 0.4 GB
Binary (IEC): 400 MB = 0.3906 GB
In the decimal standard (used by storage makers and Google), 1 MB = 1000 of the next unit down, so 400 MB = 0.4 GB. Operating systems use the binary standard (×1024), giving 0.3906 GB.
megabytes to gigabytes table
Decimal (SI) values.
| MB | GB |
|---|---|
| 100 MB | 0.1 GB |
| 400 MB | 0.4 GB |
| 500 MB | 0.5 GB |
| 1000 MB | 1 GB |
Convert any size
Need a different value or unit? The full data storage converter handles bits, bytes, KB, MB, GB, TB and PB.
Frequently asked questions
How many gigabytes is 400 MB?+
400 MB equals 0.4 GB using the decimal (SI) standard that drive makers and Google use, or 0.3906 GB using the binary standard that operating systems use.
Why are there two answers?+
Storage is measured two ways: decimal (1 GB = 1000 of the next unit down) and binary (1 GB = 1024). Hard-drive and SSD capacities are advertised in decimal, while Windows and other systems report sizes in binary — which is why a "1 TB" drive shows as about 931 GB in your operating system.