How many MB are in a GB?
1,000 MB if you're using decimal units, and 1,024 MiB if you're using binary units. Both are in everyday use, which is why the question has no single answer:
- Decimal: 1 GB = 1,000 MB. Powers of 1,000, the SI-style units used for storage capacities and data-transfer rates.
- Binary: 1 GiB = 1,024 MiB. Powers of 1,024, whose standardized IEC names are MiB and GiB.
Match the convention to the source of your number. Storage manufacturers and network providers commonly use decimal units, while binary units are common in computing contexts. When the distinction matters, use the explicit IEC names KiB, MiB and GiB.
How to convert GB to MB
Decimal: MB = GB × 1,000Binary: MiB = GiB × 1,024 Multiply, because a megabyte is smaller than a gigabyte, so the number gets larger. Going the other way — MB to GB — you divide by the same figure.
Worked example, 2.5 GB in decimal units: 2.5 × 1,000 = 2,500 MB. For 2.5 GiB, the binary conversion is 2.5 × 1,024 = 2,560 MiB.
GB to MB conversion table
| Gigabytes | Decimal (MB) | Binary (MiB) |
|---|---|---|
| 0.5 GB | 500 MB | 512 MiB |
| 1 GB | 1,000 MB | 1,024 MiB |
| 2 GB | 2,000 MB | 2,048 MiB |
| 4 GB | 4,000 MB | 4,096 MiB |
| 5 GB | 5,000 MB | 5,120 MiB |
| 8 GB | 8,000 MB | 8,192 MiB |
| 10 GB | 10,000 MB | 10,240 MiB |
| 16 GB | 16,000 MB | 16,384 MiB |
| 20 GB | 20,000 MB | 20,480 MiB |
| 32 GB | 32,000 MB | 32,768 MiB |
| 50 GB | 50,000 MB | 51,200 MiB |
| 64 GB | 64,000 MB | 65,536 MiB |
| 100 GB | 100,000 MB | 102,400 MiB |
| 128 GB | 128,000 MB | 131,072 MiB |
| 256 GB | 256,000 MB | 262,144 MiB |
| 500 GB | 500,000 MB | 512,000 MiB |
| 512 GB | 512,000 MB | 524,288 MiB |
| 1,000 GB | 1,000,000 MB | 1,024,000 MiB |
Why the two answers differ by 2.4%
1,024 is 2.4% larger than 1,000, so a figure converted in binary units comes out 2.4% higher than the same figure converted in decimal ones. That gap is small enough to ignore for a rough estimate and large enough to matter when you're checking whether something fits.
The gap compounds at each step up, which is why it's much more visible at the terabyte level: a drive sold as 1 TB contains 1,000,000,000,000 bytes. Expressed in binary units, that is about 931.32 GiB.
If you want to see how a file size affects download duration, use our Download Time Calculator.
Frequently asked questions
Is 1 GB 1,000 MB or 1,024 MB?
Both, depending on the unit system. In decimal units 1 GB is 1,000 MB. In binary units the same step is 1,024, and the strictly correct names for those units are GiB and MiB. Use whichever matches the source of your number.
How many MB is 5 GB?
5,000 MB in decimal units, or 5,120 MiB in binary units. Multiply by 1,000 or by 1,024 respectively.
How do I convert MB back to GB?
Divide instead of multiplying — by 1,000 for decimal units or 1,024 for binary. The converter above has a swap button that reverses the direction and carries the result across.
Which should I use for my mobile data allowance?
Mobile data allowances are normally expressed using decimal units, so 5 GB means 5,000 MB. If you're working with a transfer speed rather than a storage amount, see our Data Transfer Calculator.