Capricorn and Aquarius compatibility gets a lot of searches, and most pages answer with a score. We asked three other questions. How many US couples are Capricorn and Aquarius at all? Did real marriages favor the pair? And what do the old books say about these two signs side by side?
The first answer is the surprise. Out of 66 ways to pair two different signs, this one is the rarest in US births. About 1 random US couple in 83 is Capricorn and Aquarius. The second answer is no: in 10.3 million British marriages, the pair sat within noise of chance. The third answer is a quirk. The two signs sit side by side, and they share one ruler, Saturn.
This guide shows how we got each answer, so you can check it. Read it as a lens, not a forecast. Astrology is not a science, and no study has shown that a sign predicts how a couple will do.
The short answer, in six lines
| Question | What we found. |
|---|---|
| How common is a Capricorn and Aquarius couple? | About 1 random US couple in 83, or 1.21 percent. |
| Where does that rank? | Last of the 66 pairs of two different signs. |
| What would an even split of signs give? | 1 couple in 72, or 1.39 percent. |
| Did real marriages favor the pair? | No: a small surplus, inside the range chance allows. |
| How far apart are the signs? | One sign, or 30 degrees: they are next door. |
| Who rules the two signs? | Saturn rules both of them. |
How many couples are Capricorn and Aquarius?
Your Sun sign is the slice of the sky the Sun stood in when you were born. Each slice is 30 degrees wide. Capricorn season runs from about December 21 to January 19. Aquarius season runs from about January 20 to February 18. The exact hour moves a little each year. Our zodiac signs guide checks each date against the real sky.
The twelve signs are not the same size in births. We counted 62.2 million US births, day by day, from 2000 to 2014. Here is what the two signs got.
| Source of the births | Share born Capricorn | Share born Aquarius | Chance a random couple is Capricorn and Aquarius. |
|---|---|---|---|
| US births 2000 to 2014, 62.2 million, by exact date | 7.63 percent | 7.93 percent | 1.21 percent, or 1 in 83. |
| If all twelve signs were equal | 8.33 percent | 8.33 percent | 1.39 percent, or 1 in 72. |
Why multiply by two? A couple can be a Capricorn woman with an Aquarius man, or the other way round. Both count. So the chance is two times the Capricorn share times the Aquarius share.
Capricorn is the rarest Sun sign in US births. Aquarius and Sagittarius come next, less than a tenth of a point apart. When you pair the rarest sign with one of the next rarest, you get the rarest pair. That is all there is to it.
Where the pair sits among all 78
Twelve signs make 78 pairs. There are 66 pairs of two different signs and 12 pairs of the same sign. Same sign pairs are all rarer, since the math gives them no factor of two.
The very rarest of the 78 is a same sign pair, as our guide to Capricorn and Capricorn compatibility shows.
| Rank of 78 | Pair | Share of random US couples. |
|---|---|---|
| 1st, the most common | Leo and Virgo | 1.60 percent, or 1 in 62. |
| 65th | Sagittarius and Capricorn | 1.21 percent, or 1 in 82. |
| 66th, rarest of two different signs | Capricorn and Aquarius | 1.21 percent, or 1 in 83. |
| 78th, the rarest of all | Capricorn and Capricorn | 0.58 percent, or 1 in 172. |
Our page on Leo and Virgo compatibility covers the other end of the list. A Leo and Virgo couple is about a third more common than a Capricorn and Aquarius one.
Be fair to the gap at the bottom. Sagittarius and Capricorn trail by a hair. In a second file, from the National Center for Health Statistics for 1994 to 2003, the two swap places. Both files agree on the main point. The pair lands at 1 in 83 either way, near the very bottom of the 66.
Why winter births are scarce
Two things set a sign’s share of births. The first is how long the Sun stays in the sign. The second is how many babies are born each day in that season. Capricorn loses on both counts.
The Sun moves fastest in January
Earth’s path around the Sun is not a perfect circle. Earth comes closest to the Sun in early January, and it moves fastest then. So the Sun seems to cross Capricorn and Aquarius in a hurry.
| Sign | Average days the Sun spends there, 2000 to 2014 | Share of the year. |
|---|---|---|
| Capricorn | 29.44 days, the shortest stay | 8.06 percent. |
| Sagittarius | 29.56 days | 8.09 percent. |
| Aquarius | 29.59 days, the third shortest | 8.10 percent. |
| Cancer, for contrast | 31.45 days, the longest stay | 8.61 percent. |
These stays cover 2000 to 2014, the same years as the birth file, so they line up with the births above. Over the site’s reference window, 1600 to 2400, the four figures are 29.446, 29.557, 29.592 and 31.451 days. Our Capricorn sign guide explains the orbit in detail.
Fewer babies per day, mostly on holidays
The second cause is on the ground. US births dip at the turn of the year. We took the average day across the whole year as 100. Then we scored each winter day against it.
| Date or stretch | Births per day, with the yearly average as 100. |
|---|---|
| December 25 | 57, the lowest day of the year. |
| January 1 | 68, a third below normal. |
| December 24 | 71, well below normal. |
| The whole Capricorn stretch, December 22 to January 19 | 94, or 6 percent short. |
| The same stretch, without five holiday dates | 98.5, close to normal. |
| The whole Aquarius stretch, January 20 to February 17 | 98, close to normal. |
The five holiday dates are December 24, 25, 26 and 31, and January 1. Doctors and parents plan fewer induced births and planned C-sections on those days. Take those five days out, and Capricorn’s daily count is close to Aquarius. So the shortfall in Capricorn births is part orbit and part holiday calendar. None of it comes from the stars.
What ten million marriages showed
A birth count tells you how common the pair is. It does not tell you if the pair works. For that, the best test we know is a British one.
In 2007, the sociologist David Voas, then at the University of Manchester, studied the married couples in the 2001 census of England and Wales. That was 10.3 million couples, with the birth date of both partners. He asked a plain thing. Do some sign pairs marry more than chance would predict? Do others marry less?
His answer was no. The one clear excess was couples of the same sign. He traced it to form errors, such as one birthday typed in for both partners. Once he took those out, the table matched chance. His paper is titled “Ten million marriages: a test of astrological love signs.” The Skeptical Inquirer ran a version of it in March 2008.
We pulled the Capricorn and Aquarius cells from his cleaned table, Table 7. The expected count is what you would get if people chose partners with no regard to sign.
| Couples in the 2001 census, cleaned | Found | Expected by chance | Gap. |
|---|---|---|---|
| Capricorn wife, Aquarius husband | 63,381 couples | 62,988 couples | 393 couples over. |
| Aquarius wife, Capricorn husband | 63,722 couples | 63,376 couples | 346 couples over. |
| Both ways together | 127,103 couples | 126,364 couples | 0.59 percent over. |
Is that surplus a sign of fate? Voas gives the scale. With 9.5 million couples spread over 144 cells, a cell can drift by up to 450 couples by chance alone. Both cells stay inside that band. The pair ranks fourth of 66 for surplus, and that still means nothing firm. Among 66 pairs, a few must come out on top by luck. The honest reading is simple. Capricorns and Aquarians marry each other at about the rate the calendar sets.
One more note on Britain. There, Capricorn was not the rarest sign in the census. Scorpio was. Birth seasons differ by country and by era. That is one more reason to read our US figures as a guide to the US.
Next door: 30 degrees apart
Count from Capricorn to Aquarius and you pass no sign at all. They touch. By sign, the gap is 30 degrees. Modern astrologers call this link a semisextile, a minor aspect worth half a sextile.
Ptolemy, the Greek writer of the second century, did not count it. In his book, the Tetrabiblos, he lists four aspects: the opposition, the trine, the square and the sextile. Signs one apart share none of them. He calls such signs “disjunct” or “alien.” He says signs one apart are “as it were averted from one another.” In plain words, they turn their backs.
His other two links do not help this pair. Ptolemy pairs some signs as “commanding” and “obeying.” In the list from his translator, Capricorn obeys Cancer and Aquarius obeys Gemini. He pairs other signs that “behold” each other, since the Sun gives them days of equal length. There, Aquarius pairs with Sagittarius, and Capricorn has no partner at all. William Lilly counts these mirror pairs by degree instead. Then Capricorn mirrors Sagittarius, and Aquarius mirrors Scorpio. Either way, the two signs have no bond of sight.
Is every Capricorn and Aquarius pair 30 degrees apart?
By sign, yes. By degree, no. A Capricorn Sun at 0 degrees and an Aquarius Sun at 29 degrees sit 59 degrees apart. A Capricorn Sun at 29 degrees and an Aquarius Sun at 0 degrees sit just 1 degree apart.
Modern astrologers allow a margin, called an orb, around each angle. We weighted real US birth dates and got the same shares as our other sign pairs. About 19 percent of couples fall within 3 degrees of the 30 degree mark. About 36 percent fall within 6 degrees, 46 percent within 8, and 56 percent within 10.
This pair has one twist the others lack. Since the signs touch, some Suns sit right across the border. About 3.6 percent of Capricorn and Aquarius couples have their Suns within 8 degrees of each other. Many astrologers would read that as a conjunction, a meeting of the two Suns, not a semisextile.
Two signs, one ruler
This is the part that sets the pair apart in the old books. In Ptolemy’s plan, each planet owns two signs. The Sun and the Moon own one each. Saturn gets Capricorn and Aquarius.
Ptolemy gives the reason. Cancer and Leo, the signs of the Moon and the Sun, are the warmest, since they sit closest to the top of the sky for a Greek reader. Saturn is the cold planet, the farthest from the lights. So it gets the two signs opposite them. Capricorn faces Cancer, and Aquarius faces Leo. Ptolemy adds that these signs are “cold and wintry.”
Look at the rulers around the circle and the pair stands out. Capricorn and Aquarius are the only neighbor signs with a single ruler. Every other planet’s two signs sit apart. Mars owns Aries and Scorpio. Venus owns Taurus and Libra. Jupiter owns Sagittarius and Pisces. Our page on Capricorn and Aquarius Venus placements makes the same point for Venus.
So the pair holds a small paradox. By aspect, the signs turn their backs. By ruler, they answer to one lord. William Lilly, in Christian Astrology in 1647, calls Aquarius Saturn’s day house and Capricorn its night house. One lord, two shifts.
The rest of the old score
A ruler is only one of the ranks a planet can hold in a sign. Here is the full list from Ptolemy, checked against Lilly.
| Rank in the old books | In Capricorn | In Aquarius. |
|---|---|---|
| Ruler, the planet at home | Saturn, its night house | Saturn, its day house. |
| Exalted guest, a planet at its best | Mars | No planet. |
| Planet in exile, far from home | The Moon, whose sign is across | The Sun, whose sign is across. |
| Planet in fall, at its weakest | Jupiter | No planet. |
| Lords of the element by day and night | Venus and the Moon, for earth | Saturn and Mercury, for air. |
One line stands out. In Aquarius, Saturn holds two ranks at once: owner of the sign and day lord of the air group. Ptolemy himself makes this point, when he scolds older tables for passing Saturn over in Aquarius. In Capricorn, Saturn holds only the one rank. The Moon and Venus lead the earth group there.
How many have Saturn at home?
A planet is at home when it sits in a sign it rules. For this pair, that means Saturn in Capricorn for the Capricorn partner, and Saturn in Aquarius for the Aquarius partner.
Saturn takes about 29.5 years to go round the sky. It sits in any one sign for a couple of years. So only a small share of people have it at home. We counted over 27 full laps of Saturn, from 1613 to 2408, so no part of a lap tips the scale.
| Partner | Share born with Saturn in their own Sun sign. |
|---|---|
| Capricorn | 10.15 percent, about 1 in 10. |
| Aquarius | 9.87 percent, about 1 in 10. |
Our Aquarius sign guide gives the same 9.87 percent. Saturn sits in one of the two signs about 18 percent of the time. Couples born within a year or two of each other share a Saturn sign, so where Saturn sits is worth a look in both charts.
What the pair means as a symbol
With the numbers set out, here is what astrologers read into the pair. Treat it as a way to talk, not a rule.
The two signs differ in element. Capricorn is earth: in the old texts, cold and dry. Aquarius is air: hot and wet. Stephen Arroyo, in his book on the four elements, links earth to what is solid and useful. He links air to ideas, links between people and the wish to share a view. On this reading, one partner builds and the other thinks out loud.
The two signs differ in mode too. Capricorn is a cardinal sign, one that opens a season. Cardinal signs are read as keen to start and to lead. Aquarius is a fixed sign, one that falls in the middle of a season. Fixed signs are read as steady, firm and slow to change course.
The shared ruler adds the common thread. Saturn is the planet of time, limits and keeping your word. Liz Greene reads Saturn as the part of us that grows through slow effort. Robert Hand links it to form and structure. In Capricorn, astrologers read Saturn as the builder of the plan. In Aquarius, they read it as the keeper of the rules a group lives by.
The same symbols name the friction points. A cardinal sign can want to move now, while a fixed sign wants to hold the line. An earth sign can want proof, while an air sign wants a good idea. Both partners, on this reading, can go quiet and cool when hurt, since Saturn is the cold planet. These are themes to talk about, not verdicts on a couple.
Look past the Sun signs
A Sun sign is one point in a chart. The Moon, Venus and Mars signs add a lot about daily life and love. Your Moon sign, the sign the Moon was in at birth, speaks to moods and needs. We cover Capricorn and Aquarius Moon signs in a separate guide.
For this pair, one planet is worth a close look: Saturn. It rules both Sun signs. Where it sits in each chart, by sign and by house, is part of the story the Sun signs leave out.
How we measured
You can redo every number on this page.
For birth shares, we used US births for every date from 2000 to 2014, 62.2 million in all, from the Social Security file compiled by the site FiveThirtyEight. We checked the pattern against the National Center for Health Statistics file for 1994 to 2003. That second file gives the pair 1.21 percent too, or 1 in 83. We placed each birth day on the sky using the real hour the Sun enters each sign, in US Central time. A day on the cusp was split by the share of hours on each side. The pair chance is two times the Capricorn share times the Aquarius share. The rank compares all 78 pairs, the same sign pairs included.
For the holiday effect, we took the average births for each calendar date over the 15 years. We divided by the average for all dates. The Sun stays come from the times the Sun entered each sign, from 2000 to 2014, the years of the birth file.
For the orbs, we spread each day’s births over the hours of that day. We placed the Sun for each slot, then paired every Capricorn slot with every Aquarius slot. We read off how far apart the two Suns sit.
For Saturn, we stepped through time every six hours from 1613 to 2408, which is 27 whole laps. We used the astronomy-engine code library. At each step we noted the sign of the Sun and of Saturn.
The marriage counts come from Table 7 of the Voas paper, his cleaned version of census table C0792. Rows are wives and columns are husbands. The expected count for each cell is the row total times the column total, divided by the grand total. The quotes from Ptolemy come from the Tetrabiblos, Book 1, chapters 13 to 18, in the Robbins translation, with his notes 80, 83, 88 and 101.
The limits are real. Birth shares are not the same as shares of adults who date, and many couples meet across borders. The US figures are a close guide, not a census of couples.
Questions people ask
Are Capricorn and Aquarius compatible?
No study has found that Sun signs predict how a couple does. The largest test, 10.3 million marriages in England and Wales, found Capricorn and Aquarius couples within the range of chance. As a symbol, the pair joins two neighbor signs that share one ruler, Saturn.
What percentage of couples are Capricorn and Aquarius?
About 1.21 percent of random US pairings, or 1 in 83, based on 62.2 million US births from 2000 to 2014. That is the rarest of the 66 pairs of two different signs. An even split of signs would give 1 in 72.
Why is a Capricorn and Aquarius couple so rare?
Capricorn is the rarest Sun sign in US births, and Aquarius is close behind. The Sun crosses both signs fast in January. Births dip on the winter holidays, with Christmas Day at 57 percent of an average day.
Do Capricorn and Aquarius share a ruler?
Yes. In traditional astrology, Saturn rules both signs. Aquarius is its day house and Capricorn its night house. They are the only neighbor signs with one ruler.
What aspect do Capricorn and Aquarius make?
By sign, a semisextile of 30 degrees, a minor aspect. Ptolemy did not count it and called such signs disjunct. By degree, the Suns sit from under 1 to nearly 60 degrees apart, and about 3.6 percent of couples come within 8 degrees.
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