How to use the data storage converter
- Type a size in the From box. 1 is entered for you, and decimals and commas both work, such as 0.5 or 1,500.
- Pick the unit you have in the first menu and the unit you want in the second. The menus are grouped into decimal bytes, binary bytes and bits, so GB and GiB are easy to tell apart.
- To work backwards, type in the To box instead.
- Press Swap units to flip the direction, or read The same size in other units for every unit at once.
How the conversion works
Every unit is stored as a whole number of bits (a byte is 8 bits). The tool multiplies by the From unit's bits and divides by the To unit's bits using exact whole-number arithmetic, so 1 TiB shows as 1,099,511,627,776 bytes, not 1,099,511,628,000. Decimal prefixes (KB, MB, GB, TB, PB, EB) are powers of 1,000, as in the NIST: Metric (SI) prefixes. Binary prefixes (KiB, MiB, GiB, TiB, PiB, EiB) are powers of 1,024, as described by NIST: Prefixes for binary multiples. A lowercase b is a bit and a capital B is a byte, so Mb is a megabit and MB a megabyte. Answers of up to 15 significant digits are exact, and longer ones are rounded to 15.
Worked example with the default values
With 1 in the From box, Gigabyte (GB) as the From unit and Megabyte (MB) as the To unit, the result line reads 1 GB = 1,000 MB, because 1 GB is 1,000,000,000 bytes and 1 MB is 1,000,000 bytes. The reverse line reads 1 MB = 0.001 GB. The grid shows the same size as 0.931322574615479 GiB and 953.67431640625 MiB, which is why decimal and binary answers never match.
Decimal versus binary units
| Decimal | Size | Binary | Size | Gap |
|---|---|---|---|---|
| KB | 1,000 bytes | KiB | 1,024 bytes | 2.4% |
| MB | 1,000,000 bytes | MiB | 1,048,576 bytes | 4.86% |
| GB | 1,000,000,000 bytes | GiB | 1,073,741,824 bytes | 7.37% |
| TB | 1,000,000,000,000 bytes | TiB | 1,099,511,627,776 bytes | 9.95% |
Drive label versus what Windows shows
| Label on the drive | Shown in Windows |
|---|---|
| 256 GB | 238.42 GiB |
| 512 GB | 476.84 GiB |
| 1 TB | 931.32 GiB |
| 2 TB | 1,862.65 GiB |
For raw bits and hex, try the number base converter or the binary to text converter. If a photo is too big for an upload limit, the image compressor can shrink it, and the unit converter covers other kinds of unit.
Limits and edge cases
A size cannot be negative, so a minus sign gets a message. Letters, currency symbols and slashes are blocked with a hint, and numbers above 1,000,000,000,000,000,000,000,000 are refused. The KB label follows common use, while strict SI writes kB. Real disk space and downloads differ from these figures because of file system and protocol overhead.
Sources: NIST: Metric (SI) prefixes; NIST: Prefixes for binary multiples.
Data Storage Converter FAQ
How many MB are in a GB?
In decimal units, 1 GB is 1,000 MB. In binary units, 1 GiB is 1,024 MiB. Drive makers and macOS use the decimal counts, while Windows uses the binary counts and labels them GB.
Why does my 1 TB drive show 931 GB?
The drive holds 1,000,000,000,000 bytes. Windows divides by 1,073,741,824 (1,024 cubed) and labels the answer GB, so it shows 931.32 GiB as 931 GB. Nothing is missing, the units just differ.
Is a kilobyte 1,000 or 1,024 bytes?
By the SI definition a kilobyte is 1,000 bytes. The 1,024 byte unit is the kibibyte (KiB). The two meanings were mixed for decades, which is why this page lists both.
How long does a 1 GB download take at 100 Mbps?
100 megabits per second is 12.5 megabytes per second (divide by 8), so 1 GB (1,000 MB) takes 80 seconds at the full line rate. Real downloads are usually slower because of overhead.
What is the difference between a bit and a byte?
A byte is 8 bits. Network speeds use bits (Mbps) and file sizes use bytes (MB), so divide megabits by 8 to get megabytes. A lowercase b means bit and a capital B means byte.