Weeks to Common Years (wk to yr (365))
1 week equals 0.01917808219 common years (rounded).
How to convert weeks to common years
To convert weeks to common years, multiply the number of weeks by 0.01917808219. The factor is rounded to 10 significant digits. To go the other way, multiply common years by 52.14285714 (rounded).
common years = weeks × 0.01917808219
Example: 10 weeks = 0.1917808219 common years.
Months and years are not constant. This site uses the average Gregorian year of 365.2425 days, so one 'year' converts to 365.2425 days, not 365; use 'common year' for exactly 365 days.
About these units
Week (wk)
Seven days. The seven-day week comes from the ancient Near East and is nearly universal in the modern calendar.
Nothing in the sky produces a seven-day cycle, which makes the week a human invention with a contested pedigree. Babylonians marked the 7th, 14th, 21st and 28th of the lunar month as special, but that was not a continuous cycle. A continuous seven-day cycle tied to the Sabbath is attested in Judaism by the 6th century BC at the latest, and scholars disagree on whether it was borrowed from Babylon or developed independently. The Romans later used a week named for the Sun, the Moon and the five visible planets, and in AD 321 Emperor Constantine decreed it across the empire.
A week is seven days, or 604,800 seconds, and it divides evenly into neither months nor years, which is why calendars shift against it. The ISO 8601 standard starts each week on Monday and assigns week 1 to the week containing the year's first Thursday, so some years have a week 53. Other societies used different lengths: Rome had an eight-day market cycle, and revolutionary France used a ten-day week from 1793 to 1802. The English word comes from Old English wice, meaning a turn or succession.
1 week = 604,800 seconds (exactly).
Sources: Wikipedia: Week; Wikipedia: ISO week date
Common Year (yr (365))
A calendar year of exactly 365 days, without a leap day.
Calendar makers needed whole numbers of days, so the common year is simply 365 of them, or 31,536,000 seconds at 86,400 seconds per day. It makes up 303 of every 400 years in the Gregorian calendar. Because 365 is 52 weeks plus one day, a common year begins and ends on the same weekday, and each date falls one weekday later than the year before.
The trouble is that the Earth takes about 365.24 days to complete a cycle of seasons, so a common year runs roughly 5 hours, 48 minutes and 46 seconds short of the tropical year. The shortfall adds up to a full day in about four years, which is why leap years exist. NIST lists the 365-day year as an exact conversion, while its tropical and sidereal years are measured quantities that differ in the fifth significant figure.
1 common year = 31,536,000 seconds (exactly).
Sources: Wikipedia: Common year; NIST SP 811 Appendix B.8: factors for units outside the SI
Related conversions
- Common years to weeks (reverse)
- Weeks to seconds
- Weeks to minutes
- Weeks to hours
- Weeks to days
- Weeks to months
- Weeks to years
- Weeks to milliseconds
- Weeks to microseconds
- Weeks to nanoseconds
- Weeks to decades
- Weeks to centuries
- Weeks to millennia
- Seconds to common years
- Minutes to common years
- Hours to common years
- Days to common years
- Months to common years
- Years to common years
See all time units.