Weeks to Lustra (wk to lustrum)

1 week equals 0.00383306981 lustra (rounded).

1 week = 0.00383306981 lustra

How to convert weeks to lustra

To convert weeks to lustra, multiply the number of weeks by 0.00383306981. The factor is rounded to 10 significant digits. To go the other way, multiply lustra by 260.8875.

lustra = weeks × 0.00383306981

Example: 10 weeks = 0.0383306981 lustra.

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)

CalendarCurrent unit

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

Lustrum (lustrum)

Ancient RomanHistorical unit (no longer in standard use)

Five years, the interval between Roman censuses and the ritual purification that closed each one.

Roman censors counted citizens and their property about every five years, and the period between counts took the name lustrum. The word is tied to a Latin verb for purifying, because each census ended with a solemn purification of the people, often performed through the sacrifice of a bull, a ram and a pig in the Campus Martius. Ancient tradition credited the first one to King Servius Tullius in 566 BC.

Censors held office from 443 BC, and a later law cut their term from a full lustrum to 18 months. The interval was not always kept: Livy recorded only 21 lustra between 443 BC and 294 BC where 30 might have been expected, and some censuses took place without the ritual. The last censors were appointed in 23 BC under Augustus. In modern English the word survives for any five-year span. Using a Gregorian year of 365.2425 days, one lustrum is about 157.8 million seconds, which is the figure used here.

1 lustrum = 157,784,760 seconds (exactly).

Sources: Wikipedia: Lustrum; Wikipedia: Roman census

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