How Rare Is Your Zodiac Sign? US Birth Data

By Dana Whitmore · 2026-08-18

A grid of blank paper squares on a corkboard, with a cluster of squares near one edge circled in blue ink

If your sign feels like everyone's sign, there's a real reason - and it has nothing to do with the stars.

This page answers the "rarest zodiac sign" question with actual US birth records, names the dataset behind the claim, and explains the cause instead of handing you another ranking.

The story is demographics, not astrology.

The Short Answer: Yes, Some Signs Get More Birthdays - And It's Not Astrology

Births cluster in the late-summer-to-early-fall window - Virgo and Libra season - and thin out in deep winter, from late December through mid-February, when Capricorn and Aquarius sit on the calendar.

That pattern is well supported in the public record.

The punchline: this is hospital scheduling and conception timing, not cosmic design. About one in three US births is a C-section, and hospitals don't schedule elective procedures on Christmas. Meanwhile, conceptions rise in the colder months, and at an average gestation of about 38 weeks, that lands births the following September.

Here's the boundary the rest of this page depends on: the direction is solid, but an exact percentage gap between the most and least common sign is not publicly sourceable. I will not invent one, and you should not trust a page that does.

Where These Numbers Come From - and Where They Stop

The counts behind every "rarest sign" page trace back to one compilation: FiveThirtyEight's births dataset, stitched from CDC/NCHS daily birth records covering 1994 through 2003 and Social Security Administration records covering 2000 through 2014.

The dataset gives you day-by-day birth counts - the only public source with that level of detail.

The recency limit, stated plainly because nobody else states it: the series ends in 2014. No equally granular public day-of-year distribution was found for later years. The CDC still publishes natality reports (Births: Final Data for 2023 is available), but not in a form that settles the "which sign gets the most birthdays" question.

Two secondary analyses of that same dataset circulate widely: The Daily Viz visualization by Matt Stiles, which mapped individual birthdays onto a calendar, and the sachsac GitHub project, which grouped the daily counts into zodiac signs.

Both are independent work built on the FiveThirtyEight data. Neither is the primary source - that's the CDC and Social Security Administration records - but both are what readers actually meet when they search this question.

I spent an afternoon chasing "rarest signs in order" rankings back to their sources. Two pages confidently contradicted each other on both ends of the list, and neither named a dataset or a date range. That's when I decided this page would do one thing the rest don't: tell you where the data stops.

For the full record of what controlled testing says about astrology as a system, explore the rest of Astrology, Honestly.

Which Signs the Birth Data Actually Favors

Season window Signs What the data shows Source
Late summer to early fall Virgo, Libra The highest birth counts; August is the highest-count month and September holds most of the top individual birthdays sachsac/Astrology_and_Birth_Months, built on the FiveThirtyEight 1994-2014 dataset
Fall and early winter Scorpio, Sagittarius Mid-range; the available analysis does not separate these signs from each other Same analysis
Deep winter Capricorn, Aquarius The lowest counts; February is the lowest-count month Same analysis
Spring and early summer Pisces through Leo Mid-range; the available analysis does not separate these signs from each other Same analysis

Virgo comes out highest and Capricorn lowest in the best available sign-level analysis - the sachsac project, built on the same 1994-2014 data I just named. August records the most births overall and February the fewest, which is exactly why the winter signs land at the bottom.

The safe framing is "the winter signs are the rarest," not crowning one winner. Sources disagree on the exact sign, and one widely shared page contradicts every other source on both ends of the list. I will not link it, and you should not trust a ranking that stands alone.

September really is the peak. An analysis of the dataset found 9 of the 10 most common individual US birthdays fall in September, with September 9 averaging about 12,300 births a year over the period. The exception is July 7.

Seventeen of the top 30 fall in September. If you want the full September calendar breakdown, that page is here.

Now the honest gap: no public source gives a trustworthy percentage difference between the most and least common sign. Not the FiveThirtyEight data, not the sachsac analysis, not the CDC natality reports. A page that hands you a precise percentage - "Aquarius is 8.5% rarer than Virgo" - is not sourcing it.

That's the fastest tell in the checklist below.

Cause One: Hospitals Don't Schedule Births on Christmas

About one in three US births in the United States is a C-section, and elective C-sections and inductions get scheduled around public holidays rather than on them. The mechanism is straightforward: if a birth can be scheduled, it won't be scheduled on December 25.

The size of the effect: roughly 30-40% fewer babies are born on December 25 than on the year's peak day, according to a 2020 piece in The Conversation.

The peer-reviewed version - a study by Jacobson, Kogelnik and Royer published in the Journal of Labor Economics in 2021 - found about 18% fewer births on and around major US holidays in California birth-certificate data, with roughly half of that from scheduled C-sections.

The study found no adverse health effects from the displacement.

The load-bearing detail: the "missing" holiday births are displaced, not prevented. They reappear roughly 11 days before to 16 days after the holiday. This is a scheduling story, not a conception story.

Nobody decided not to have a baby in late December - the hospital moved the date to a neighboring week.

That displacement thins out the late-December-to-early-January window, which is exactly where Capricorn sits on the calendar. Aquarius follows immediately after. The winter trough is a hospital calendar, not a cosmic one.

Cause Two: More Conceptions When It's Cold

Conceptions rise in the colder, shorter-day months - about November and December - and at an average gestation of about 38 weeks, that lands births the following September. The pattern is directional and well corroborated: the September peak and the late-fall-to-January trough line up exactly where you would expect them if conception timing were seasonal.

Birth timing does leave a few real traces on the body, and they are far smaller than any horoscope suggests - the appearance page walks through the measured ones.

The two causes reinforce each other rather than competing. Scheduling moves births off specific days - Christmas, New Year's Day - and back onto the surrounding weeks. Conception timing moves the whole season, producing the September concentration nine months after the November-December cluster.

What you will not find on this page: precise month-by-month deviation percentages. Those figures circulate online, but they came from an unsourced synthesis, not a fetched primary document. The directional claim - more September babies, fewer deep-winter ones - is solid.

The specific monthly deviation number is not.

Cause What the evidence shows What it moves Source
Holiday scheduling About 18% fewer births on and around major US holidays (Jacobson, Kogelnik & Royer 2021); roughly 30-40% fewer on December 25 than on the peak day (The Conversation); about half from scheduled C-sections Births off specific days and back onto neighboring ones (11 days before to 16 days after) Jacobson et al., Journal of Labor Economics 2021; The Conversation 2020
Conception seasonality Conceptions cluster in the colder months; about 38 weeks to birth The whole season, producing the September peak The Conversation 2020

So Is Your Sign Rare? How to Read Any "Rarest Sign" Ranking

If you are a Capricorn or an Aquarius, you are, on this data, in a slightly thinner slice of the calendar. That fact is about your parents' December, not about your character. The only thing the data describes is how many people share your birthday window.

I don't read daily horoscopes - I like the zodiac as a mirror, not a map. A rare sign doesn't make you rare. It makes your birthday less common, and that's all.

Here's how to tell whether a "rarest sign" page knows what it's talking about. Run these five checks in under a minute:

Source-checking checklist:

  1. Does the page name its dataset, and does it name the agency behind it? If it says "studies show" or "according to data" without naming the study or the data, that's a tell.
  2. Does it say which years the data covers? The detailed public series runs 1994-2014. A page that implies the finding is more current than that is dressing up an older figure.
  3. Does it explain a cause, or only assert an order? Hospital scheduling and conception timing are the documented mechanisms. A page that skips the explanation probably skipped the source.
  4. Does it agree with other pages on which sign is rarest - and if not, does it say so? Sources disagree on the exact winner, and at least one widely shared page contradicts every other source. A page that acknowledges the disagreement is doing the work.
  5. Does it give you a precise percentage gap? If yes, ask where that number came from, because no public source supports one.

If a ranking fails three or more of those checks, it's not sourced.

Myth vs fact: Five things the "rarest sign" posts get wrong

  • Myth: Your sign is rare because of the stars.
    Fact: Birth counts vary by season because of hospital scheduling and conception timing. The zodiac is just the calendar those births land on.

  • Myth: Aquarius is the rarest sign, exactly X% of people.
    Fact: Sources disagree on which winter sign is lowest, and no reliable public source gives a percentage gap at all.

  • Myth: Nobody is born on Christmas.
    Fact: About 30-40% fewer are born on December 25 than on the peak day, and most of those births are rescheduled to the surrounding weeks, not prevented.

  • Myth: These are current CDC numbers.
    Fact: The granular public series runs 1994-2014, and no equally detailed later distribution was found.

  • Myth: A rare sign makes you rare.
    Fact: The only thing the data describes is how many people share a birthday window.

For the psychological reason why "rare sign" rankings feel meaningful even when they're not sourced, that piece is here.

FAQ: Rare Signs, Common Signs, and the Numbers Behind Them

So which zodiac sign is actually the rarest?

The deep-winter signs, Capricorn and Aquarius. The best available analysis of the 1994-2014 data puts Capricorn lowest, but sources disagree on the exact winner, so "the winter signs" is the honest answer, not a single crown. February is the lowest-count month, and that's where both signs sit.

How much rarer is it - what's the actual percentage?

Nobody can tell you honestly from the public data. No reliable source gives a gap between the most and least common sign - not the FiveThirtyEight dataset, not the secondary analyses built on it, not the CDC natality reports. A page that hands you a precise percentage is not sourcing it, and that is the fastest tell in the checklist above.

Why does every website give me a different rarest sign?

Because most of them assert a ranking without naming a dataset or a date range.

At least one widely shared page contradicts every other source on both ends of the list - Cancer as the most common and Aquarius as the rarest, when every other analysis puts late-summer signs at the top and deep-winter signs at the bottom.

Naming the data is what makes the answer checkable.

Is September really the biggest birthday month?

It is the densest cluster in the record. An analysis of the same dataset found 9 of the 10 most common individual birthdays fall in September, with September 9 averaging about 12,300 births a year over the period. The exception is July 7.

Seventeen of the top 30 fall in September. August is the highest-count month overall, which is why Virgo and Libra land at the top of the sign table.

Are these numbers still true today?

The detailed public series ends in 2014, and no equally granular later distribution was found. Treat the direction as durable - hospital scheduling and conception timing have not reversed - and the specific daily figures as a snapshot of 1994-2014, which is exactly how this page states them. I wanted a current number.

I found that the series stops in 2014, and I decided to say so instead of dressing up an older figure as today's.

Does having a rare sign mean anything about me?

No. The data describes how many people share your birthday window, and that number was set by hospital calendars and by which months people conceive in - a mirror, not a map. Being born in a low-count window says nothing about your character, your luck, or your future.

Your sign isn't rare or common because of anything the sky did - it's the shape of one country's hospital calendar.

If that's the kind of answer you like, here's why "rare sign" rankings feel meaningful even when they're not sourced, and here's the full record of controlled testing on astrology.

Sources

Western tropical astrology content on this site is entertainment and self-reflection. Sign descriptions are traditional symbolic conventions, not scientific claims about a person. The data on this page describes birth-count patterns driven by hospital scheduling and conception timing - demographics, not astrology.

Dana Whitmore

is YouHoroscope's editorial voice: plain-spoken, curious, and allergic to mystification. No astrology credentials are claimed here - the published date tables do the proving.