Born on December 21
A cusp birthday. In most years the Sun crosses from Sagittarius into Capricorn during December 21, so people born this day are one or the other depending on the hour. At noon UTC it's Sagittarius in 90% of years.
Sagittarius or Capricorn? Check your year
The Sun's entry into Capricorn shifts by a few hours from year to year. Find your birth year, convert your birth time to UTC, and compare: born before the time shown, you're Sagittarius; after it, Capricorn. Years missing from the list had the crossing on a neighbouring day (the Sun was in one sign for the whole of December 21).
Not sure about the time zone or the minutes? Compute your chart — it does the conversion and settles the sign.
Your sign: Sagittarius (or Capricorn)
The mutable fire sign that aims at the bigger picture and refuses to be domesticated.
A Sagittarius Sun is built around expansion and meaning. You're the friend who has lived in three countries, who keeps reading philosophy at 2am, who wants to know what people actually think rather than what they're supposed to say. Your optimism is real — not the brittle "everything happens for a reason" kind, but a genuine sense that life is interesting and worth showing up for.
- ElementFire
- ModalityMutable
- RulerJupiter
- SeasonNovember 22 – December 21
Full Sagittarius guide → · What a Sagittarius birth chart looks like → · Capricorn guide →
Your decan: the third decan of Sagittarius
Each sign is divided into three 10° decans, and each decan has a sub-ruler that shades the sign's core. Degrees 20–30 of Sagittarius belong to Saturn: where you face limitation and, through facing it, build mastery. Read it as Sagittarius with a Saturn accent — the fire core is unchanged, the emphasis moves.
Ten of Wands
Burden · Responsibility · Completion. The card assigned to this ten-degree slice of the zodiac — a birthday card in the same sense a sun sign is a birthday sign: one lens on the date, not a verdict.
Read the Ten of Wands in full on My Day Check →What the date can't tell you
The Sun is one placement out of ten. Your Moon sign changes every two to three days, so Sagittarians born on December 21 in different years have different Moons; your rising sign changes every two hours and needs a birth time and place. Those two carry most of what people mean by "personality" in a chart.
Or browse the twelve possibilities: Sagittarius Sun with each Moon →
Classic matches for a December 21 birthday
By sun sign, Sagittarius pairs most easily with Aries, Leo, Libra, Aquarius. Sun-sign compatibility is the coarse layer; the couple reading compares both full charts.
Common questions
Is December 21 Sagittarius or Capricorn?
Both are possible. On December 21 the Sun moves from Sagittarius into Capricorn in most years, at a time that ranges from 08:19 UTC to 23:38 UTC UTC across 1980–2030 (in some years the crossing falls on the neighbouring day). Convert your birth time to UTC and compare it with the crossing for your year in the table above — before it you're Sagittarius, after it Capricorn.
What zodiac sign is December 21?
December 21 is a cusp day between Sagittarius and Capricorn; at noon UTC it falls in Sagittarius in 90% of years between 1980 and 2030. Your birth year and hour decide it.
What decan is December 21?
The third decan of Sagittarius (20°–30°), sub-ruled by Saturn. Decans divide each sign into three 10° slices; the sub-ruler adds a second flavour to the sign's core — here where you face limitation and, through facing it, build mastery.
What tarot card is December 21?
In the Golden Dawn system each decan has a minor arcana card: for the third decan of Sagittarius it is the Ten of Wands (burden, responsibility, completion). It's a birthday card in the same way a sun sign is — one lens, not a verdict.
Does everyone born on December 21 have the same chart?
No. They share the Sun in Sagittarius or Capricorn, but the Moon changes sign every two to three days, the rising sign every two hours, and the outer planets by year. Two people born December 21 in different years can have almost nothing else in common in their charts.