Zepto

Zepto (symbol z) is a prefix in the SI system of units denoting a factor of 10-21.

Adopted in 1991, it comes from the French sept, meaning seven, since it is equal to 1/10007.

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

See also

SI prefix

See also: Zepto, 1000000 (number), 1000 (number), 100 (number), 10 (number), 1991, 1 (number), Atto, Billiard