Recognised as Date
31 December 1101
- Tuesday
- Q4
- Common year
- Week 1
- Capricorn
31 December 1101 falls on a Tuesday in the proleptic Gregorian calendar, which did not yet exist at the time. It is day 365 of 365 in 1101, falling in week 1 and quarter 4. Its Unix timestamp is -27,391,564,800.
Calendar position
Day of the weekTuesdayproleptic Gregorian; contemporaries used the Julian calendar and would have named a different day
Day of the month31st
Day of the year365 of 365
Days remaining in the year0
Days elapsed in the year364
ISO week numberWeek 1 of 1102ISO weeks can belong to the neighbouring year
Week of the month5th
Occurrence in the month5th Tuesday, and the last of the month
QuarterQ4 1101
Year1101
Days in the month31
Leap yearNo, 365 days
This date in other formats
ISO 86011101-12-31
British (D/M/Y)31/12/1101
American (M/D/Y)12/31/1101
Long formTuesday 31st December 1101
RFC 2822Tue, 31 Dec 1101 00:00:00 GMT
Compact11011231
In wordsthe 31st of December, one thousand, one hundred and one
Julian calendar equivalent24 December 1101the date contemporaries would have written, before the Gregorian calendar existed
This date in other calendars
Hebrew2 Shevat 4862the Hebrew calendar has been fully algorithmic since the ninth century, so this is exact
Islamic (tabular)1 Rabi I 495 AHthe tabular reckoning; the calendar in religious use begins each month on an actual crescent sighting, so expect a day either way
Persian (arithmetic)9 Dey 480the arithmetic (Birashk) calendar; the official Solar Hijri calendar takes its new year from the astronomical equinox at Tehran
Rata Die402,131days since 1 January 1 CE in the proleptic Gregorian calendar, the pivot every conversion here runs through
Unix time & day counts
Unix timestamp-27,391,564,800seconds since 1 January 1970, midnight UTC
Unix timestamp (ms)-27,391,564,800,000
Relationship to the epoch317,032 days before the Unix epoch
Julian Day Number2,123,556midnight UTC
Days since 1 January 1900-291,465
Days since 1 January 2000-327,989
Moon phase
PhaseWaxing crescentthe same phase everywhere on Earth at the same instant
Illuminated at 12:00 UTC7%≈to about 1%, by Meeus
Waxing or waningWaxing
Moon age at 12:00 UTC2.2 dayssince the previous new moon
Previous new moon29 December 1101
Next new moon27 January 1102
Previous full moon14 December 1101
Next full moon13 January 1102
Lit side, Northern HemisphereRight
Lit side, Southern HemisphereLeftthe same Moon seen from the other side of the equator; near the equator the lit side points up or down rather than to one side
PrecisionDates onlybefore 1700 or after 2150 the Earth's rotation is not known well enough to give a time, and a phase near midnight can land a day either side
Relative to today
These values depend on today’s date and change daily.
Today20 September 2026
Days ago337,748 days
In other terms924 years and 257 days
Weeks48249.7 weeks ago
Anniversary this yearin 102 days
Years elapsed924 complete years
Seasons & signs
Zodiac signCapricornEarth sign
Chinese zodiac yearSnakethe animal changes at Chinese New Year, not 1 January
Season (Northern Hemisphere)Wintermeteorological seasons, by whole months
Season (Southern Hemisphere)Summer
Easter Sunday that year24 March 1101
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