Fractions

Prefix
Factor
Fraction
centi
10–2
1/100 (part per hundred)
milli
10–3
1/1,000 (part per thousand)
micro
10–6
1/1,000,000 (ppm, part per million)
nano
10–9
1/1,000,000,000 (ppb, part per billion)
pico
10–12
1/1,000,000,000,000 (ppt, part per trillion)
femto
10–15
1/1,000,000,000,000,000 (ppq, part per quadrillion)
atto
10–18
1/1,000,000,000,000,000,000 (part per quintillion)