💾 Data storage
GB to MB Converter
Enter gigabytes and press Convert to get megabytes. 1 GB is 1000 MB in decimal storage and 1024 MiB in binary notation.
About the GB to MB Converter
There are two answers to “how many MB in a GB” and both are in use. Drive manufacturers count in powers of ten — 1 GB = 1000 MB — while Windows counts in powers of two and labels the result MB, so the same file appears smaller than its stated size. The IEC names for the binary units are MiB and GiB, but consumer software rarely uses them.
That gap is 4.9% at the gigabyte level, which is why a “500 GB” SSD shows about 465 GB in Windows. It is not missing space, just a different definition — confirmed by the fact that the discrepancy grows with each unit step.
How the calculation works
- 1 GB = 1000 MB = 1,000,000,000 bytes (decimal)
- 1 GiB = 1024 MiB = 1,073,741,824 bytes (binary)
- Decimal GB ÷ 1.073741824 = binary GiB
Reference values
| Gigabytes (decimal) | Megabytes | Binary GiB |
|---|---|---|
| 1 GB | 1,000 MB | 0.93 GiB |
| 2 GB | 2,000 MB | 1.86 GiB |
| 8 GB | 8,000 MB | 7.45 GiB |
| 16 GB | 16,000 MB | 14.90 GiB |
| 64 GB | 64,000 MB | 59.60 GiB |
| 128 GB | 128,000 MB | 119.21 GiB |
| 256 GB | 256,000 MB | 238.42 GiB |
| 512 GB | 512,000 MB | 476.84 GiB |
Worked examples
- A 512 GB phone holds 512,000 MB in decimal terms, which Windows reports as 476.8 GiB.
- A 4.7 GB film is 4,700 MB, and a 700 MB file fits in 0.7 GB.
- A 2 GB data bundle is 2,000 MB, or about 33 hours of web browsing at 60 MB/h.
Checking the answer by hand
Multiply by 1,000 for decimal megabytes, or by 1,024 for binary. If the two answers are more than 2.4% apart you have used the wrong pair for the same unit system — the gap between MB and MiB is 4.9%, and it doubles again at the gigabyte step.
Common mistakes
- Blaming the manufacturer for "missing" capacity. A 1 TB drive is 1,000,000,000,000 bytes, which is 931 GiB.
- Mixing systems in one calculation, such as 1,000 MB in and 1,024 MB out.
- Assuming a 100 Mbps connection downloads at 100 MB/s. It is 12.5 MB/s.
A last check on the numbers: 37 Gigabyte (10⁹) works out to 37,000 Megabyte (10⁶), and reversing that with the same factor brings you back to 37 Gigabyte (10⁹). Because Gigabyte (10⁹) to Megabyte (10⁶) is a single multiplication, any tool that gives a different figure for the same input is rounding somewhere in the middle rather than only at the end.