MB to GB Converter
Convert megabytes to gigabytes. Enter a size in MB and choose decimal (1000) or binary (1024); the tool shows your selected result, the other convention for comparison, and the total in bytes.
Example: with Size in MB 1500 · Convention Decimal / SI (1 GB = 1000 MB) → Result: 1.5 GB (decimal, 1000).
- Other conventionBinary mode: 1.465 GiB
- In bytesAbout 1,500,000,000 bytes (1 MB = 1,000,000 bytes)
Computed by the calculator below using its default values. Change any input to see your own numbers.
Two standards exist. Decimal (SI) says 1 GB = 1000 MB, used by drive makers and networks. Binary (IEC) says 1 GiB = 1024 MB, used by Windows and RAM. Same data, different label.
Why two answers for one size
There are two definitions of a gigabyte. The decimal or SI standard sets 1 GB = 1000 MB, which drive manufacturers, networks, and the metric system use. The binary standard sets 1 GiB = 1024 MB, matching how memory is addressed and how Windows reports sizes. For the same file, decimal gives a slightly larger GB number than binary gives GiB.
The gap grows with size: it is about 2.4 percent per step, so a drive sold as 1000 GB shows as roughly 931 GiB in an operating system that counts in 1024s. Neither is wrong; they are different units. The IEC names GiB, MiB, and KiB exist specifically to make the binary meaning explicit and end the confusion.
How it’s calculated
Decimal (SI): GB = MB ÷ 1000. Binary (IEC): GiB = MB ÷ 1024. The tool computes both and displays the selected convention as the main result. The byte total uses the decimal definition, 1 MB = 1,000,000 bytes.
Interprets the input MB as decimal megabytes for the byte count. Storage vendors use decimal; operating systems such as Windows report binary, which is why a new drive looks smaller than advertised.
MB to GB in both conventions
| MB | GB (decimal 1000) | GiB (binary 1024) |
|---|---|---|
| 1,000 | 1 | 0.9766 |
| 1,024 | 1.024 | 1 |
| 1,500 | 1.5 | 1.4648 |
| 5,000 | 5 | 4.8828 |
| 10,000 | 10 | 9.7656 |
Decimal: GB = MB/1000. Binary: GiB = MB/1024.
Common mistakes
- Assuming one fixed answer — MB to GB depends on the 1000 vs 1024 convention.
- Comparing a drive advertised in decimal GB with an OS reading in binary GiB and thinking space is missing.
- Mixing the units, dividing by 1024 but calling the result GB rather than GiB.
- Confusing megabytes (MB, storage) with megabits (Mb, speed).
Frequently asked questions
How many MB are in a GB?
It depends on the convention. Decimal (SI) uses 1 GB = 1000 MB; binary (IEC) uses 1 GiB = 1024 MB. Drive makers use decimal, Windows uses binary.
Why does my hard drive show less space than advertised?
Manufacturers count in decimal (1000), while the operating system counts in binary (1024). A 1000 GB drive shows as about 931 GiB, though no space is actually lost.
What is the difference between GB and GiB?
GB is the decimal gigabyte (1000 MB). GiB is the binary gibibyte (1024 MiB). GiB is about 7.4 percent larger than GB at the gigabyte scale.
Which convention should I use?
Use decimal for storage and network specs, and binary when matching what your operating system or RAM reports. This tool shows both so you can compare.