Hours to Lustra (h to lustrum)

1 hour equals 0.00002281589172 lustra (rounded).

1 hour = 0.00002281589172 lustra

How to convert hours to lustra

To convert hours to lustra, multiply the number of hours by 0.00002281589172. The factor is rounded to 10 significant digits. To go the other way, multiply lustra by 43,829.1.

lustra = hours × 0.00002281589172

Example: 10 hours = 0.0002281589172 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

Hour (h)

Metric (SI)Current unit

60 minutes or 3,600 seconds, one twenty-fourth of a mean solar day.

Egyptian astronomers gave us the twelve. Coffin lids from about 2150 BC show the night divided into exactly 12 intervals, tied to the rising of star groups called decans, and the day was later split into 12 hours with sundials. These were seasonal hours, a twelfth of the daylight, so a summer hour was longer than a winter one. The word itself comes from Greek hora, originally any span of time, through Latin and Old French into English in the 13th century.

Equal hours of 1/24 of a day were probably first proposed by Hipparchus, and mechanical clocks made them the practical choice, since a clock showing seasonal hours had to be readjusted every morning and evening. Today the hour is exactly 3,600 seconds and is a non-SI unit accepted for use with the SI. Civil time still bends it a little: UTC hours have lasted 3,601 seconds 27 times since 1972 to keep clocks within 0.9 seconds of the Earth's rotation. In practice we use it for working shifts, travel times and electricity bills measured in kilowatt-hours.

1 hour = 3,600 seconds (exactly).

Sources: Wikipedia: Hour; BIPM: SI Brochure, 9th edition

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

Related conversions

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