Kilo

Kilo is also the letter K in the NATO phonetic alphabet.
Kilo class is a type of naval submarine made in Russia.

Kilo (symbol: k) is a prefix in the SI system denoting 103 or 1000. For example:

Adopted in 1795, it comes from the Greek χίλιοι, meaning thousand.

"Kilo" is often used by itself as an abbreviation for "kilogram". Also, technical people often use the term "k", pronounced like the letter, to refer to a thousand of something, especially units of money or population. On the other hand, the kilometre (US: "kilometer") is often abbreviated to "klick" in American usage, especially in the military.

SI prefixes
10n Prefix Symbol Short scale Long scale Decimal Equivalent
1024 yotta Y Septillion Quadrillion 1 000 000 000 000 000 000 000 000
1021 zetta Z Sextillion Trilliard (thousand trillion) 1 000 000 000 000 000 000 000
1018 exa E Quintillion Trillion 1 000 000 000 000 000 000
1015 peta P Quadrillion Billiard (thousand billion) 1 000 000 000 000 000
1012 tera T Trillion Billion 1 000 000 000 000
109 giga G Billion Milliard (thousand million) 1 000 000 000
106 mega M Million 1 000 000
103 kilo k Thousand 1 000
102 hecto h Hundred 100
101 deca, deka da Ten 10
100 none none One 1
10−1 deci d Tenth 0.1
10−2 centi c Hundredth 0.01
10−3 milli m Thousandth 0.001
10−6 micro µ Millionth 0.000 001
10−9 nano n Billionth Milliardth 0.000 000 001
10−12 pico p Trillionth Billionth 0.000 000 000 001
10−15 femto f Quadrillionth Billiardth 0.000 000 000 000 001
10−18 atto a Quintillionth Trillionth 0.000 000 000 000 000 001
10−21 zepto z Sextillionth Trilliardth 0.000 000 000 000 000 000 001
10−24 yocto y Septillionth Quadrillionth 0.000 000 000 000 000 000 000 001

Use in computing

In computing, kilo does not always exactly denote 1000 but is usually equivalent to 1024 (210), most often when denoting storage. For example, a kilobyte is 1024 bytes, not 1000 bytes. A common convention is to use k for 1000 and K for 1024, but this is not universally recognised and cannot be relied upon. The prefix kibi for 1024 has also been introduced (with the abbreviation Ki), but has not gained much popularity.

See Binary prefix for more details.

See also: Kilo, 1000000 (number), 1000 (number), 100 (number), 10 (number), 1795, 1 (number), 1 E3, Atto