Decimal or binary: two ways to count bytes
Byte units have two meanings. Decimal (SI) steps by 1,000, which is how drive makers, macOS, iOS, Android and network gear count. Binary steps by 1,024, which is how Windows and RAM count; the IEC gives these sizes their own names (KiB, MiB, GiB) so they cannot be confused. Bits are always decimal: 1 Kb = 1,000 b, and 1 B = 8 b. The converter above has a switch for the mode.
| Unit | Decimal (SI) | Binary |
|---|---|---|
| KB kilobyte | 1,000 B | 1,024 B |
| MB megabyte | 1,000,000 B | 1,048,576 B |
| GB gigabyte | 1,000,000,000 B | 1,073,741,824 B |
| TB terabyte | 1,000,000,000,000 B | 1,099,511,627,776 B |
| PB petabyte | 1 × 10¹⁵ B | 1.125899907 × 10¹⁵ B |
| EB exabyte | 1 × 10¹⁸ B | 1.152921505 × 10¹⁸ B |
Popular file size conversions
Data storage units
Digital storage is counted in bits and bytes (1 byte = 8 bits). There are two ways to count bytes. Decimal (SI) prefixes step by 1,000: 1 KB = 1,000 B and 1 GB = 1,000 MB, which is how drive makers, macOS, iOS and Android report sizes. Binary prefixes step by 1,024: 1 KB = 1,024 B and 1 GB = 1,024 MB, which is how Windows and RAM count (the IEC names for these are KiB, MiB and GiB). Bits are always decimal: 1 Kb = 1,000 b.
| Unit | Symbol | In bits | Definition |
|---|---|---|---|
| Bit | bit | 1 bit | A single binary digit, 0 or 1. |
| Nibble | nibble | 4 bit | Four bits, one hexadecimal digit. |
| Byte | B | 8 bit | Eight bits. |
| Kilobit | kb | 1,000 bit | One thousand bits. |
| Kilobyte | KB | 8,000 bit | In decimal (SI) mode 1,000 bytes; in binary mode 1,024 bytes, as Windows and RAM count. The unambiguous binary name is kibibyte (KiB). |
| Megabit | Mb | 1,000,000 bit | One million bits. Internet speeds are sold in megabits per second. |
| Megabyte | MB | 8,000,000 bit | In decimal mode 1,000,000 bytes (1,000 KB); in binary mode 1,048,576 bytes (1,024 KB). |
| Gigabit | Gb | 1,000,000,000 bit | |
| Gigabyte | GB | 8,000,000,000 bit | In decimal mode 1,000,000,000 bytes (1,000 MB); in binary mode 1,073,741,824 bytes (1,024 MB). |
| Terabit | Tb | 1,000,000,000,000 bit | |
| Terabyte | TB | 8,000,000,000,000 bit | In decimal mode 1,000 GB, which is how drives are sold; in binary mode 1,024 GB. |
| Petabyte | PB | 8 × 10¹⁵ bit | In decimal mode 1,000 TB; in binary mode 1,024 TB. |
| Exabyte | EB | 8 × 10¹⁸ bit | |
| Kibibyte | KiB | 8,192 bit | Exactly 1,024 bytes (binary prefix). |
| Mebibyte | MiB | 8,388,608 bit | Exactly 1,048,576 bytes, or 1,024 KiB. |
| Gibibyte | GiB | 8,589,934,592 bit | Exactly 1,073,741,824 bytes, or 1,024 MiB. What Windows displays as GB. |
| Tebibyte | TiB | 8,796,093,022,000 bit | Exactly 1,024 GiB. |
| Pebibyte | PiB | 9.007199255 × 10¹⁵ bit |
Calculate with file size
The smart calculator does arithmetic across file size units and picks a sensible unit for the answer. Try 1 TB / 4 to GiB.
Questions and answers
Which file size units can I convert?
All 18: bits, nibbles, bytes, kilobits, kilobytes, megabits, megabytes, gigabits, gigabytes, terabits, terabytes, petabytes, exabytes, kibibytes, mebibytes, gibibytes, tebibytes, pebibytes.
What is the SI unit of file size?
This converter uses the bit (bit) as its base unit. Digital storage is counted in bits and bytes (1 byte = 8 bits). There are two ways to count bytes. Decimal (SI) prefixes step by 1,000: 1 KB = 1,000 B and 1 GB = 1,000 MB, which is how drive makers, macOS, iOS and Android report sizes. Binary prefixes step by 1,024: 1 KB = 1,024 B and 1 GB = 1,024 MB, which is how Windows and RAM count (the IEC names for these are KiB, MiB and GiB). Bits are always decimal: 1 Kb = 1,000 b.
Is 1 GB equal to 1,000 MB or 1,024 MB?
Both are in use. In decimal (SI) counting, which drive makers, macOS, iOS and Android use, 1 GB = 1,000 MB. In binary counting, which Windows and RAM use, 1 GB = 1,024 MB; the unambiguous IEC name for that size is the gibibyte (GiB). ConvertEasy has a Decimal / Binary switch so KB, MB, GB and TB follow whichever you need, while KiB, MiB and GiB are always binary.
Are kilobits 1,000 or 1,024 bits?
ConvertEasy treats bits as decimal in both modes: 1 Kb = 1,000 b, 1 Mb = 1,000 Kb. A byte is always 8 bits, so only byte units (KB, MB, GB…) change with the switch.
How precise are the results?
Factors are the exact legal definitions where one exists (an inch is exactly 2.54 cm, a pound exactly 0.45359237 kg). Results show 10 significant digits by default; the precision menu offers 4 to 15.
Does the file size converter work offline?
Yes. ConvertEasy is a progressive web app: after your first visit it keeps working with no connection, and you can install it to your home screen from the browser menu.