1 megabyte equals 0.001 gigabytes. Enter a value below to convert instantly.
Megabytes to gigabytes is a decimal conversion on this site: 1 GB is 1,000 MB, following the SI meaning of 'giga'. Operating systems often use 1,024 instead and still write 'GB', which is the root of nearly every disagreement about how big a file or a drive really is.
Need the other direction? Convert gigabyte to megabyte →
Multiply the number of megabytes by 0.001 to get gigabytes.
| Megabytes (MB) | Gigabytes (GB) |
|---|---|
| 1 | 0.001 |
| 2 | 0.002 |
| 5 | 0.005 |
| 10 | 0.01 |
| 50 | 0.05 |
| 100 | 0.1 |
| 500 | 0.5 |
| 1,000 | 1 |
A 1 TB drive holds 1,000,000,000,000 bytes, which Windows reports as 931 GB because it is dividing by 1,024 three times and calling the result GB. Nothing is missing; the two numbers use different definitions of the same prefix.
Carriers bill in decimal GB. A 20 GB plan is 20,000 MB, and phone usage counters generally agree because mobile operating systems also use decimal for data accounting.
A 4.7 GB DVD image is 4.7 decimal GB, or about 4.38 GiB. Software that reports the binary figure makes the same file look smaller, which causes confusion when checking whether it will fit.
Memory is genuinely binary — a 16 GB stick is 16 GiB, because memory is addressed in powers of two. Storage is decimal. The same abbreviation means different things in the two contexts, and both are conventional.
Values people actually look up, with the reason each one comes up. Every figure is calculated with the same engine as the converter above.
| Megabyte (MB) | Gigabyte (GB) | What it is |
|---|---|---|
| 1 | 0.001 | The base conversion |
| 100 | 0.1 | A short video |
| 500 | 0.5 | A large application |
| 700 | 0.7 | A CD's capacity |
| 1,000 | 1 | Exactly one gigabyte |
| 4,700 | 4.7 | A single-layer DVD |
| 25,000 | 25 | A single-layer Blu-ray |
| 50,000 | 50 | A dual-layer Blu-ray |
The SI prefixes are decimal: kilo is 1,000, mega is 1,000,000, giga is 1,000,000,000. Storage manufacturers and networking use them that way. Operating systems historically used powers of 1,024 — 2¹⁰, 2²⁰, 2³⁰ — because memory addressing is binary, but kept the decimal prefix names. IEC 80000-13 resolved the ambiguity in 1998 by introducing kibi, mebi and gibi for the binary values, so 1 GiB = 1,073,741,824 bytes while 1 GB = 1,000,000,000 bytes. Windows still reports GiB values labelled 'GB'; macOS and most Linux distributions switched to decimal GB.
Both definitions are exact within themselves; the imprecision is in the labelling. When a figure matters — a backup that must fit, a quota, a contract — state the unit unambiguously as GB or GiB, or give the byte count. The gap grows with scale: 2.4% at kilo, 4.9% at mega, 7.4% at giga and 10% at tera.
A 1 TB drive really does contain a trillion bytes. The 931 figure is the same capacity divided by 1,024³ and mislabelled.
MB is megabytes; Mb or Mbit is megabits, an eighth as much. Storage is in bytes, network speed is in bits.
Data caps and transfer volumes are decimal. Converting a 20 GB allowance as 20 GiB overstates it by 7.4%.
Content on this page last reviewed 12 August 2026. Spotted an error? Report it — see also how these values are calculated.
1 MB expressed in every other data storage unit on this site.
The megabyte (MB) is a Metric unit of data storage.
The gigabyte (GB) is a Metric unit of data storage.
Under the SI prefixes used by storage manufacturers and this converter, 1 GB is 1,000 MB. The 1,024 figure is one gibibyte (GiB), a binary unit defined by IEC 80000-13 — many systems still display GiB values labelled 'GB'.
A single-layer DVD holds about 4,700 MB, marketed as 4.7 GB. In binary units that is about 4.38 GiB, which is why a DVD image can look too small in some file managers.
Use decimal (1,000-based) for storage capacity, network transfers and data allowances. Use binary (1,024-based) for RAM. When it matters, write GiB explicitly rather than relying on context.
One megabyte equals 0.001 gigabytes.
Multiply the number of megabytes by 0.001 to get gigabytes.
One gigabyte equals 1,000 megabytes.
This conversion is common when sizing drives, files, backups, and memory.