Multiples of bits  

SI decimal prefixes  IEC binary prefixes  
Name (Symbol) 
Standard SI 
Binary usage 
Name (Symbol) 
Value 
kilobit (kbit)  10^{3}  2^{10}  kibibit (Kibit)  2^{10} 
megabit (Mbit)  10^{6}  2^{20}  mebibit (Mibit)  2^{20} 
gigabit (Gbit)  10^{9}  2^{30}  gibibit (Gibit)  2^{30} 
terabit (Tbit)  10^{12}  2^{40}  tebibit (Tibit)  2^{40} 
petabit (Pbit)  10^{15}  2^{50}  pebibit (Pibit)  2^{50} 
exabit (Ebit)  10^{18}  2^{60}  exbibit (Eibit)  2^{60} 
zettabit (Zbit)  10^{21}  2^{70}  zebibit (Zibit)  2^{70} 
yottabit (Ybit)  10^{24}  2^{80}  yobibit (Yibit)  2^{80} 
See also: Nibble · Byte ·
Multiples of bytes Orders of magnitude of data 
Gigabit is a unit of digital information storage, with the symbol Gbit (or Gb).
1 gigabit = 10^{9} = 1,000,000,000 bits (which is equal to 125 decimal megabytes or 122 binary mebibytes, as 8 bits equals one byte)
The gigabit is closely related to the gibibit, which is unambiguously equal to 2^{30} bits = 1,073,741,824 bits.
Note that the difference between a billion bits and a gibibit is greater than 7%. This is sufficient to make it economically compelling to represent certain classes of storage devices in (true) gigabits or gigabytes rather than gibibits/gibibytes. RAM and flash chips are usually required to have a capacity that is a power of two, but other devices like hard disk drives need not.
