Gigabytes and 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.
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.
Worked example
Convert 2.5 GB: 2.5 × 1,000 = 2,500, so 2.5 gigabytes is 2,500 megabytes. Likewise 2 GB = 2,000 MB.
Estimating in your head
The factor is a power of ten, so just move the decimal point 3 places to the right: 2.5 GB = 2,500 MB.
Going the other way
To convert megabytes to gigabytes, divide by 1,000 (or multiply by 0.001). The swap button between the boxes opens that page.
How this works
MB = GB × 1,000
1 GB = 1,000,000,000 B and 1 MB = 1,000,000 B, both by definition, so the factor is their ratio: 1,000 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 megabytes are in a gigabyte?
1 gigabyte = 1,000 megabytes, exactly. The value follows from the unit definitions, so it never changes.
How do I convert gigabytes to megabytes?
Multiply by 1,000. For example, 2 GB × 1,000 = 2,000 MB.
What is 10 GB in megabytes?
10 GB = 10,000 MB. 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/gb-to-mb/