Is 22 December Sagittarius or Capricorn?

It depends on the year. Enter your date of birth here and it is decided from the Sun's position that year. Where the date falls on a cusp, the result says so.

Born on a cusp, may I read both signs?

As a way of reading, certainly. The text produced here is built on the one sign decided by the position at noon, so compare the other yourself.

How is it decided for a birth outside Japan?

The calculation uses noon Japan time. For a birth in a distant time zone close to the turn of the date, the result can fall either way.

Born on a cusp — decided by calculation, not by a table of dates

2026.09.11 updated · 5 min read

AoiBalancedClear analysis and kind words, held in the right balance

AoiAoi here. People born on a cusp often tell us that different books give different answers. Neither is wrong, so let me start with why.

A table of signs will say something like Capricorn from 22 December to 19 January. Another source will say from the twenty-third. Someone born on that day ends up with a different sign depending where they look.

Neither is in error. The change of sign is simply not on the same date every year.

Signs are fixed by angle, not by date

The twelve signs divide the Sun's path into twelve. Each is thirty degrees, and the period during which the Sun is in that section is that sign. The divisions are angles, not dates.

The Earth does not take exactly 365 days to go round the Sun; it takes about 365.2422. That fraction pushes the moment the Sun reaches the same angle about six hours later each year.

Four years of that is corrected by a leap day. So the date of a change moves back and forth by about a day on a four-year cycle. Tables differ by a day depending which year they were written from.

Method	How a cusp is handled	What can happen
Consulting a fixed table	Cut on the same date every year	In some years it is out, giving the wrong sign
Calculating the Sun's position	Cut at the actual time that year	Correct for any year of birth

This service calculates it

This service decides the sign by calculating the angle the Sun stood at on the day of birth. It holds no table of dates. The calculation is the same machinery used to find the solar terms for the Four Pillars.

Because the same calculation is reused, astrology and the Four Pillars never disagree about the calendar. Holding a separate table for each method is how such discrepancies arise.

Being calculated, it decides a birth in 1900 and one in 2020 with the same accuracy. Nothing falls outside the range a table happens to cover.

How much does it actually move?

Here are the change dates for the last three years as this service calculates them, listing only the signs that moved. The same sign shifts back and forth by year.

Sign begins	2024	2025	2026
Aquarius	21 January	20 January	20 January
Pisces	20 February	19 February	19 February
Cancer	21 June	21 June	22 June
Scorpio	23 October	24 October	24 October
Sagittarius	22 November	22 November	23 November

Born on 21 January 2024 you are Aquarius; the same date in 2025 and 2026 is the second day of Aquarius. Conversely, 20 January is Capricorn in 2024 and Aquarius from 2025. Which year a table was built from changes the answer.

The remaining seven signs did not move across these three years. The ones that move most are those falling where the Earth's speed changes. Over a long enough span, though, every sign shifts.

Some days still cannot be settled

Even calculated, some days are left unasserted: those where the sign differs between midnight and midnight on the day of birth. Anyone born then falls either side depending on the time.

This service does not ask for a time of birth. On such days it decides by the position at noon and adds a note to the result saying the date falls on a cusp. It never quietly picks a side.

About twelve days a year fall on a cusp. If that note appears for you, read the descriptions of both signs. Whichever sits better may be nearer where the Sun actually stood.

Knowing the time of the change would settle it, and that needs a time of birth. Rather than treating the unknown as known, we chose to report the fact of the cusp as it is.

AoiThere is no need to feel that being born on a cusp leaves you half-finished. There is a reading in which you hold the qualities of both signs. Not being settled on one side can simply be taken as breadth.

Common questions

Is 22 December Sagittarius or Capricorn?: It depends on the year. Enter your date of birth here and it is decided from the Sun's position that year. Where the date falls on a cusp, the result says so.
Born on a cusp, may I read both signs?: As a way of reading, certainly. The text produced here is built on the one sign decided by the position at noon, so compare the other yourself.
How is it decided for a birth outside Japan?: The calculation uses noon Japan time. For a birth in a distant time zone close to the turn of the date, the result can fall either way.