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Use the calculator to convert time units for day, quarter, hour, week, year, etc.
| Unit | Definition |
|---|---|
| millennium | 1,000 years |
| century | 100 years |
| decade | 10 years |
| year (average) | 365.242 days or 12 months |
| common year | 365 days or 12 months |
| leap year | 366 days or 12 months |
| quarter | 3 months |
| month | 28-31 days Jan., Mar., May, Jul., Aug. Oct., Dec.—31 days Apr., Jun., Sep., Nov.—30 days. Feb.—28 days for common year and 29 days for leap year |
| week | 7 days |
| day | 24 hours or 1,440 minutes or 86,400 seconds |
| hour | 60 minutes or 3,600 seconds |
| minute | 60 seconds |
| second | base unit |
| millisecond | 10-3 second |
| microsecond | 10-6 second |
| nanosecond | 10-9 second |
| picosecond | 10-12 second |
| Unit | Length, Duration and Size | Notes |
|---|---|---|
| Planck time unit | 5.39×10−44 s | The amount of time light takes to travel one Planck length. Theoretically, this is the smallest time measurement that will ever be possible.[3] Smaller time units have no use in physics as we understand it today. |
| yoctosecond | 10−24 s | |
| 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 | Time measurement scale of the NIST strontium atomic clock. Smallest fragment of time currently measurable is 850 zeptoseconds.[1][3] |
| attosecond | 10−18 s | |
| femtosecond | 10−15 s | Pulse time on fastest lasers. |
| Svedberg | 10−13 s | Time unit used for sedimentation rates (usually of proteins). |
| picosecond | 10−12 s | |
| nanosecond | 10−9 s | 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 | Symbol is µs |
| millisecond | 10−3 s | Shortest time unit used on stopwatches. |
| 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. |
| second | 1 s | SI Base unit. |
| minute | 60 s | |
| 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.[4] |
| ke | 14 min 24 s | Usually calculated as 15 minutes, similar to "quarter" as in "a quarter past six" (6:15). |
| kilosecond | 1000 s | 16 minutes and 40 seconds |
| hour | 60 min | |
| day | 24 h | Longest unit used on stopwatches and countdowns. |
| 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 d | Occasionally calculated as 30 days. |
| quarter and season | 3 mo | |
| semester | 18 weeks | A division of the academic year.[5] Literally "six months", also used in this sense. |
| 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[6] | 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 | 16,666,666,666.6667 minutes or about 31,700 years. |
| Megannum | 106 yr | Also called "Megayear." About 1,000 millennia (plural of millennium), or 1 million years. |
| petasecond | 1015 s | About 31,700,000 years |
| galactic year | 2.3×108 yr[2] | The amount of time it takes the Solar System to orbit the center of the Milky Way Galaxy one time. |
| 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. |
| aeon | 109 yr | Also spelled "eon". Also refers to an indefinite period of time. |
| exasecond | 1018 s | About 31,700,000,000 years or 380,399,583,123.74 months |
| zettasecond | 1021 s | About 31.7 trillion years or 3,803,995,983,123,744.56 months |
| yottasecond | 1024 s | About 31.7 quadrillion years or 380,399,583,123,744,510 months |
Everyone by now presumably knows about the danger of premature optimization. I think we should be just as worried about premature design - designing too early what a program should do.
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