Unit | Length, Duration and Size | Facts |
Instant | varies | Loosely speaking, zero time (colloquially the term may be used in other ways) |
Planck time unit | 5.39 x 10−44 s | The duration light takes to travel one Planck length. Theorized to be the smallest duration measurement that will ever be possible, roughly 10−43 seconds. |
Yoctosecond | 10−24 s | |
Jiffy | varies |
in quantum physics, the duration light takes to travel one Fermi(10−15m, about the size of a nucleon) in a vacuum: about 3 × 10−24s. In electronics, the duration for one alternating current power cycle (1/60 or 1/50 of a second). Also, an informal term for any unspecified short duration. |
Zeptosecond | 10−21 s | |
Attosecond | 10−18 s | Shortest duration now measurable |
Femtosecond | 10−15 s | pulse duration on fastest lasers |
Picosecond | 10−12 s | |
Nanosecond | 10−9 s | duration for molecules to fluoresce |
Shake | 10−8 s | 10 nanoseconds. Also a casual term for a short duration. |
Microsecond | 10−6 s | |
Millisecond | 0.001 s | shortest duration unit used on stopwatches |
Centisecond | 0.01 s | used on some stopwatches |
Decisecond | 0.1 s | used on some stopwatches |
Jiffy(electronics) | ~1/50s to 1/60s | Used to measure the duration between alternating power cycles. Also a casual term for a short duration |
Second | 1 sec | SIbase unit |
Decasecond | 10 seconds | |
Minute | 60 seconds | |
Moment(historical) | 1/40th of an hour | Used by Medieval Western European computists. |
Hectosecond | 100 seconds | 1 minute and 40 seconds |
Ke | 864 seconds | traditional Chinese unit of decimal time duration, usually 1/100 of a day. 14 minutes and 24 seconds. (Nearly 1/4 of an hour.) |
Kilosecond | 1,000 seconds | 16 minutes and 40 seconds |
Hour | 60 minutes | |
Day | 24 hours | longest unit used on stopwatches and countdowns |
Week | 7 days | Also calledsennight |
Megasecond | 1,000,000 seconds | About 11.6 days |
Fortnight | 14 days | 2 weeks (more common in Great Britain) |
Lunar month | 27.2–29.5 days | Various definitions of lunar month exist. |
Month | 28–31 days | Often 30 days for financial and other calculations. |
Quarter and season | 3 months | The duration of any of the four calendar seasons; winter, spring, summer and autumn. |
Year | 12 months | |
Common year | 365 days | 52 weeks + 1 day |
Tropical year | 365.24219 days | average |
Gregorian year | 365.2425 days | average |
Julian year | 365.25 days | |
Sidereal year | 365.256363004 days | |
Leap year | 366 days | 52 weeks + 2 days |
Biennium | 2 years | A unit of time duration commonly used by legislatures |
Triennium | 3 years | |
Olympiad | 4 year cycle | |
Lustrum | 5 years | |
Decade | 10 years | |
Indiction | 15 year cycle | |
Generation | varies | about 17-35 years for humans |
Gigasecond | 1,000,000,000 seconds | About 31.7 years |
Jubilee | 50 years | |
Century | 100 years | |
Millennium | 1,000 years | also called "kiloannum" |
Terasecond | 1012 seconds | About 31,700 years |
Megaannum | 1,000,000 years | 1 million years |
Age | varies | on the geological timescale, some millions of years |
Epoch | varies | on the geological timescale, tens of millions of years |
Petasecond | 1015 seconds | About 31.7 million years |
Era | varies | on the geological timescale, several hundred millions of years |
Galactic year | Approximately 230 million years | The duration it takes the Sun to orbit the centre of the Milky Way galaxy once. |
Eon | varies | on the geological timescale, 500 million years or more.Also "an indefinite and very long period of time". |
Gigaannum | 1,000,000,000 years | 109 years |
Exasecond | 1018 seconds | roughly 31.7 x 109 years, more than twice the age of the universe (on current estimates) |
Zettasecond | 1021 seconds | About 31.7 x 1012 years |
Yottasecond | 1024 seconds | About 31.7 x 1015 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. |