Megabytes and gigabytes
A megabyte (MB) is 1,000,000 bytes, or 1,000 kB, in the decimal system. Photos, songs, app downloads and email attachment limits are measured in megabytes.
A gigabyte (GB) is 1,000,000,000 bytes, or 1,000 MB, in the decimal system. Phone storage, data plans, RAM and video files are measured in gigabytes.
Worked example
Convert 4,500 MB: 4,500 × 0.001 = 4.5, so 4,500 megabytes is 4.5 gigabytes. Likewise 1,000 MB = 1 GB.
Estimating in your head
The factor is a power of ten, so just move the decimal point 3 places to the left: 4,500 MB = 4.5 GB.
Going the other way
To convert gigabytes to megabytes, divide by 0.001 (or multiply by 1,000). The swap button between the boxes opens that page.
How this works
GB = MB × 0.001
1 MB = 1,000,000 B and 1 GB = 1,000,000,000 B, both by definition, so the factor is their ratio: 0.001 exactly. Results drop binary floating-point noise beyond 15 significant digits and display at the precision you choose (6 significant figures by default). Copy result copies the full value.
Frequently asked
How many gigabytes are in a megabyte?
1 megabyte = 0.001 gigabytes, exactly. The value follows from the unit definitions, so it never changes.
How do I convert megabytes to gigabytes?
Multiply by 0.001. For example, 1,000 MB × 0.001 = 1 GB.
What is 10,000 MB in gigabytes?
10,000 MB = 10 GB. The table next to the converter lists more common values.
Is the result rounded?
Only on screen. The page computes with the exact definitions and removes floating-point noise past 15 significant digits; pick 3 to 12 significant figures, or use Copy result for the full value.
Sources
- NIST — Prefixes for binary multiples (IEC 80000-13)
- BIPM — The International System of Units (SI Brochure), 9th edition
- Wikipedia — Byte
Reviewed Oct 17, 2026 · test vectors fixtures/units/data/mb-to-gb/