Byte Size Converter

Convert any data size between decimal SI units (1 kB = 1000 bytes) and binary IEC units (1 KiB = 1024 bytes). Both families are shown side by side so you can see the difference.

Value

Unit

= 1,000,000,000,000 bytes

Decimal units (SI): 1 kB = 1,000 bytes

B byte	1,000,000,000,000
kB kilobyte	1,000,000,000
MB megabyte	1,000,000
GB gigabyte	1,000
TB terabyte	1
PB petabyte	0.001
EB exabyte	0.000001
ZB zettabyte	0.000000001
YB yottabyte	1e-12

Binary units (IEC): 1 KiB = 1,024 bytes

B byte	1,000,000,000,000
KiB kibibyte	976,562,500
MiB mebibyte	953,674.31640625
GiB gibibyte	931.322574615479
TiB tebibyte	0.909494701772928
PiB pebibyte	0.000888178419700125
EiB exbibyte	0.000000867361737988404
ZiB zebibyte	8.47032947254e-10
YiB yobibyte	8.27180612553e-13

Bits (network speeds, per second if it's a rate)

bit bit	8,000,000,000,000
kbit kilobit	8,000,000,000
Mbit megabit	8,000,000
Gbit gigabit	8,000
Tbit terabit	8

SI vs IEC units

SI (decimal) prefixes multiply by 1,000: kilobyte (kB), megabyte (MB), gigabyte (GB). IEC (binary) prefixes multiply by 1,024: kibibyte (KiB), mebibyte (MiB), gibibyte (GiB). The difference grows with size: 1 GB is 7% smaller than 1 GiB, and 1 TB is about 9% smaller than 1 TiB.

Storage makers, macOS and network speeds use SI units. Windows and many programs show binary sizes but label them KB, MB and GB, which is why a 1 TB drive appears as about 931 GB. 1 byte = 8 bits.

Very large values are shown with up to 15 significant digits, the precision of JavaScript numbers.

How to convert byte sizes

Enter a number.
Choose its unit, for example GB or MiB.
Read the equivalent in every SI and IEC unit, and in bits.
Copy any value.

Frequently asked questions

Is 1 KB 1000 or 1024 bytes?

By the SI standard, 1 kB is 1000 bytes and 1 KiB (kibibyte) is 1024 bytes. Windows still labels binary sizes as KB, MB and GB, which is why a 1 TB drive appears as 931 GB there.

Which units do macOS, Linux and drive makers use?

Drive makers and macOS (since 10.6) use decimal units. Linux tools vary: ls -h and df -h use binary units with K/M/G labels, while some tools use SI with the --si flag.