Unit |
Length, Duration and Size |
Notes |
Planck time | 5.39×10−44 s | The amount of time light takes to travel one Planck length. |
yoctosecond | 10−24 s | One septillionth of a second. |
jiffy (physics) | 3×10−24 s | The amount of time light takes to travel one fermi (about the size of a nucleon) in a vacuum. |
zeptosecond | 10−21 s | One sextillionth of a second. Time measurement scale of the NIST strontium atomic clock. Smallest fragment of time currently measurable is 247 zeptoseconds.[1] |
attosecond | 10−18 s | One quintillionth of a second. |
femtosecond | 10−15 s | One quadrillionth of a second. Pulse time on fastest lasers. |
svedberg | 10−13 s | Time unit used for sedimentation rates (usually of proteins). |
picosecond | 10−12 s | One trillionth of a second. |
nanosecond | 10−9 s | One billionth of a second. Time for molecules to fluoresce. |
shake | 10−8 s | 10 nanoseconds, also a casual term for a short period of time. |
microsecond | 10−6 s | One millionth of a second. Symbol is µs |
centimillisecond | 10−5 s | One hundred thousandth of a second or one hundredth of a millisecond. |
decimillisecond | 10−4 s | One ten-thousandth of a second or one tenth of a millisecond. |
millisecond | 10−3 s | One thousandth of a second. Shortest time unit used on stopwatches. |
centisecond | 10−2 s | One hundredth of a second. |
jiffy (electronics) | 1/60 s or 1/50 s | Used to measure the time between alternating power cycles. Also a casual term for a short period of time. |
decisecond | 10−1 s | One tenth of a second. |
quadrisecond / semisemisecond | 0.25 s | One quarter of a second. |
semisecond / half second | 0.5 s | One half of a second. |
second | 1 s | SI Base unit. |
decasecond | 10 s | |
half a minute | 30 s | It’s known by math. |
minute | 60 s | |
milliday | 1/1000 d | Also marketed as a ".beat" by the Swatch corporation; Milliday is a more accurate name. |
moment | 1/40 solar hour (90 s on average) | Medieval unit of time used by astronomers to compute astronomical movements, length varies with the season.[2] |
hectosecond | 100 s | 1 minute and 40 seconds |
ke | 864 s | 14 minutes and 24 seconds |
kilosecond | 1000 s | 16 minutes and 40 seconds |
half an hour | 30 min | It’s known by math. |
|
|
hour | 60 min | |
decakilosecond | 104 s | Ten thousand seconds or ten kiloseconds. |
Half an day | 12 h |
Its known by math. |
day | 24 h | Longest unit used on stopwatches and countdowns. |
hectokilosecond | 105 s | One hundred thousand seconds or one hundred kiloseconds. |
week | 7 d | Also called "sennight". |
megasecond | 106 s | 277.777778333333 hours or about 1 week and 4.6 days. |
fortnight | 2 weeks | 14 days |
lunar month | 27 d 4 h 48 min – 29 d 12 h | Various definitions of lunar month exist. |
month | 28-31 days | Occasionally calculated as 30 days. |
quarter and season | 3 mo | |
quadrimester | 4 mo | |
semester | 18 weeks | A division of the academic year.[3] Literally "six months", also used in this sense. |
half year | 6 mo | |
lunar year | 354.37 days | |
year | 12 mo | 365 or 366 d |
common year | 365 d | 52 weeks and 1 day. |
tropical year | 365 d 5 h 48 min 45.216 s[4] | Average. |
Gregorian year | 365 d 5 h 49 min 12 s | Average. |
sidereal year | 365 d 6 h 9 min 9.7635456 s |
leap year | 366 d | 52 weeks and 2 d |
biennium | 2 yr | |
triennium | 3 yr | |
quadrennium | 4 yr | |
olympiad | 4 yr | |
lustrum | 5 yr | |
decade | 10 yr | |
indiction | 15 yr | |
gigasecond | 109 s | 16,666,666.6667 minutes or about 31.7 years. |
jubilee | 50 yr |
century | 100 yr | |
millennium | 1000 yr | Also called "kiloannum". |
terasecond | 1012 s | About 31,709 years. |
megaannum | 106 yr | Also called "Megayear." 1,000 millennia (plural of millennium), or 1 million years. |
petasecond | 1015 s | About 31,709,791 years. |
galactic year | 2.3×108 yr | The amount of time it takes the Solar System to orbit the center of the Milky Way Galaxy one time. Around 230,000,000 years. |
cosmological decade | varies | 10 times the length of the previous cosmological decade, with CÐ 1 beginning either 10 seconds or 10 years after the Big Bang, depending on the definition. |
gigaannum | 109 yr | Also refers to an indefinite period of time, otherwise is 1,000,000,000 years. |
exasecond | 1018 s | About 31,709,791,983 years. |
zettasecond | 1021 s | About 31,709,791,983,764 years. |
yottasecond | 1024 s | About 31,709,791,983,764,584 years. |
Age of universe |
13700000000years |
Roughly 4.35 yottaseconds |