GB to MB
Convert gigabytes to megabytes. Multiply by 1000 for decimal units, or 1024 for binary, with mobile data and file size tables.
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The formula
MB = GB × 1000In SI units a gigabyte is a thousand megabytes. If the source means binary units — a disk utility, an older manual, most of Windows — the multiplier is 1024.
| Reading | Multiplier | 5 GB becomes |
|---|---|---|
| Decimal (SI) | 1000 | 5000 MB |
| Binary | 1024 | 5120 MB |
Quick reference
| GB | MB (decimal) | MB (binary) |
|---|---|---|
| 0.5 GB | 500 MB | 512 MB |
| 1 GB | 1000 MB | 1024 MB |
| 2 GB | 2000 MB | 2048 MB |
| 5 GB | 5000 MB | 5120 MB |
| 10 GB | 10,000 MB | 10,240 MB |
| 50 GB | 50,000 MB | 51,200 MB |
| 100 GB | 100,000 MB | 102,400 MB |
The binary column is where the familiar numbers come from. 512, 1024, 2048 and 4096 look like arbitrary sizes until you notice they are powers of two — which is why memory and partition sizes land on them and file sizes do not.
Mobile data allowances
This conversion exists mostly to answer one question: how much of a plan does something use?
| Plan | Megabytes | Hours of 1080p video |
|---|---|---|
| 1 GB | 1000 MB | 0.7 |
| 5 GB | 5000 MB | 3.3 |
| 10 GB | 10,000 MB | 6.7 |
| 20 GB | 20,000 MB | 13.3 |
| 50 GB | 50,000 MB | 33.3 |
Roaming is where the arithmetic bites hardest, because add-ons are sold in megabytes at prices set per gigabyte.
Upload and download limits
Services state limits in whichever unit makes them sound generous:
| Limit | |
|---|---|
| Email attachment, typical | 25 MB |
| Gmail attachment | 25 MB |
| WhatsApp media | 2000 MB (2 GB) |
| Free file transfer services | 2000 MB (2 GB) |
A “2 GB” transfer limit is 2000 MB decimal, or 2048 MB if the service counts in binary — worth knowing when a file is right on the boundary.
Estimating in your head
Move the decimal point three places the other way. 2.5 GB is 2500 MB. Add 2.4% if the source turns out to have meant binary units.