Lustra to Years (lustrum to yr)
1 lustrum equals 5 years exactly.
How to convert lustra to years
To convert lustra to years, multiply the number of lustra by 5. This factor is exact. To go the other way, multiply years by 0.2.
years = lustra × 5
Example: 10 lustra = 50 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
Lustrum (lustrum)
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
Year (yr)
The average Gregorian calendar year of 365.2425 days (31,556,952 seconds). A common year has 365 days and a leap year 366.
A year is the Earth's trip around the Sun, but there are several versions. The tropical year, which tracks the seasons, is about 365.2422 days. The sidereal year, measured against the stars, is about 365.2564 days, roughly 20 minutes longer, because the Earth's axis precesses. Calendars must squeeze these into whole days, which is the origin of leap years. English year descends from Old English gear, while Latin annus, the source of annual, comes from a different root.
The Gregorian calendar, introduced by Pope Gregory XIII's bull of 24 February 1582, fixed the problem of Julian drift that had moved the March equinox away from 21 March and upset the date of Easter. Ten days were skipped, so Thursday 4 October was followed by Friday 15 October. Its rule of skipping leap days in century years not divisible by 400 gives a mean year of 365.2425 days, the value this site uses for the year. Britain and its empire switched in 1752 and Russia in 1918. Scientists write the year as a, with the Julian year fixed at 31,557,600 seconds.
1 year = 31,556,952 seconds (exactly).
Sources: Wikipedia: Year; Wikipedia: Gregorian calendar
Related conversions
- Years to lustra (reverse)
- Lustra to seconds
- Lustra to minutes
- Lustra to hours
- Lustra to days
- Lustra to weeks
- Lustra to months
- Seconds to years
- Minutes to years
- Hours to years
- Days to years
- Weeks to years
- Months to years
- Milliseconds to years
- Microseconds to years
- Nanoseconds to years
- Decades to years
- Centuries to years
- Millennia to years
See all time units.