Time unit conversion table
This table contains conversions between almost all time units. Some units of time are common and some are relatively rare. This is a good query tool. Time Converter
| Name of unit | Symbol | Definition | Relation to SI units |
|---|---|---|---|
| Atomic unit of time | au | ≡ a0/( α · c ) | ≈ 2.418 884254×10 −17 s |
| Callippic cycle | ≡ 441 mo (hollow) + 499 mo (full) = 76 a of 365.25 d | = 2.396 736 Gsor 2.398 3776 Gs | |
| Century | c | ≡ 100 years (100 a) | = 3.155 6952 Gs |
| Day | d | = 24 h = 1440min | = 86.4 ks |
| Day (sidereal) | d | ≡ Time needed for the Earth to rotate once around its axis, determined from successive transits of a very distant astronomical object across an observer's meridian ( International Celestial Reference Frame) | ≈ 86.1641 ks |
| Decade | dec | ≡ 10 years (10 a) | = 315.569 520 Ms |
| Fortnight | fn | ≡ 2 wk | = 1.2096 Ms |
| Helek | ≡ 1⁄ 1080h | = 3. 3s | |
| Hipparchic cycle | ≡ 4 Callippic cycles - 1 d | = 9.593 424 Gs | |
| Hour | h | ≡ 60 min | = 3.6 ks |
| Jiffy | j | ≡ 1⁄ 60s | = 16. 6ms |
| Jiffy (alternative) | ja | ≡ 1⁄ 100s | = 10 ms |
| Ke(quarter of an hour) | ≡ 1⁄ 4h = 1⁄ 96d = 15 min | = 900 s | |
| Ke (traditional) | ≡ 1⁄ 100d = 14.4 min | = 864 s | |
| Lustre; Lustrum | ≡ 5 a of 365 d | = 157.68 Ms | |
| Metonic cycle; enneadecaeteris | ≡ 110 mo (hollow) + 125 mo (full) = 6940 d ≈ 19 a | = 599.616 Ms | |
| Millennium | ≡ 1000years ( 1000 a) | = 31.556 952 Gs | |
| Milliday | md | ≡ 1⁄ 1000d | = 86.4 s |
| Minute | min | ≡ 60 s, due to leap secondssometimes 59 s or 61 s, | = 60 s |
| Moment | ≡ 90 s | = 90 s | |
| Month(full) | mo | ≡ 30 d | = 2.592 ×10 6 s |
| Month (Greg. av.) | mo | = 30.436 875 d | ≈ 2.6297 Ms |
| Month (hollow) | mo | ≡ 29 d | = 2.5056 Ms |
| Month ( synodic) | mo | Cycle time of moon phases ≈ 29.530 589 d(average) | ≈ 2.551 Ms |
| Octaeteris | = 48 mo (full) + 48 mo (hollow) + 3 mo (full) = 8 a of 365.25 d = 2922 d | = 252.4608 Ms | |
| Planck time | ≡ ( Gℏ⁄ c5) 1⁄ 2 | ≈ 1.351 211868×10 −43 s | |
| Second | s | Time of 9 192631770periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom at 0 K (but other seconds are sometimes used in astronomy). Also that time it takes for light to travel a distance of 299 792458metres. | ( SI base unit) |
| Shake | ≡ 10 −8s | = 10 ns | |
| Sigma | ≡ 10 −6s | = 1 μs | |
| Sothic cycle | ≡ 1461a of 365 d | = 460.740 96 Ts | |
| Svedberg | S | ≡ 10 −13s | = 100 fs |
| Week | wk | ≡ 7 d = 168 h = 10 080 min | = 604.8 ks |
| Year(common) | a, y, oryr | 365 d | = 31.536 Ms |
| Year (Gregorian) | a, y, oryr | = 365.2425 d average, calculated from common years (365 d) plus leap years (366 d) on most years divisible by 4. See leap yearfor details. | = 31.556 952 Ms |
| Year (Julian) | a, y, oryr | = 365.25 d average, calculated from common years (365 d) plus one leap year (366 d) every four years | = 31.5576 Ms |
| Year (leap) | a, y, oryr | 366 d | = 31.6224 Ms |
| Year (mean tropical) | a, y, oryr | Conceptually, the length of time it takes for the Sun to return to the same position in the cycle of seasons, [Converter 1]approximately 365.242 19d, each day being 86 400SI seconds | ≈ 31.556 925 Ms |
| Year (sidereal) | a, y, oryr | ≡ Time taken for Sun to return to the same position with respect to the stars of the celestial sphere, approximately 365.256 363 d | ≈ 31.558 1497632 Ms |
Notes:
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