About the gb to mb calculation
One gigabyte is exactly 1,000 megabytes, so converting between them is a single multiplication. Enter any value above and the result updates as you type. Decimal gigabyte. This is why a "1 TB" drive shows as roughly 931 GB in your operating system. Decimal megabyte — 1,000,000 bytes, the definition storage manufacturers use.
Formula
MB = GB × 1,000
1 GB = 1,000 MB
1 MB = 0.001 GBWorked example
To convert 1 GB, multiply by 1,000: 1 × 1,000 = 1,000 MB.
Frequently asked questions
How many megabytes are in a gigabyte?
There are 1,000 megabytes in one gigabyte. To convert any amount, multiply the number of gigabytes by 1,000.
How do I convert megabytes back to gigabytes?
Divide instead of multiplying, or equivalently multiply by 0.001. One megabyte is 0.001 gigabytes.
Is this conversion exact?
Yes, provided both sides use the same convention. Decimal units (KB, MB, GB) are powers of 1,000 and binary units (KiB, MiB, GiB) are powers of 1,024. Both are exact — the confusion comes from software labelling binary values with decimal names.
Is there anything that catches people out here?
These are decimal units, where 1 GB = 1,000 MB. Operating systems often use binary units where 1 GiB = 1,024 MiB, which is why a drive sold as 1 TB shows as roughly 931 GB.
Sources
- IEC 80000-13 — binary and decimal prefixes for information units