Moon phase compatibility

How it works

1. Put in your birthday and theirs. Each moon wakes up with its real phase. No date for them? Send them your moon.
2. Look at the shapes and each make your call: how many of the 15 nights will these two moons cover? The nearest call wins.
3. Take a moon each, one thumb on each, and push. Each moon only goes halfway, so it takes you both. The dark is see-through, so you watch the gap close, or not.
4. Read your pair’s name, then deal the four questions it comes with and ask each other.

What is the moon phase soulmate test?

You look up the moon phase on your birthday and on someone else’s, then lay one picture over the other. If the lit parts fill the circle, the internet says you’re soulmates. If there’s a gap, the internet is less kind. The earliest video Know Your Meme found goes back to January 2022, and the trend came back much bigger in March 2023, when a CapCut template did the overlapping for you.

That’s the whole test. There is no study behind it, and the moon doesn’t know you. It’s popular because it’s a sweet thing to do with someone, which is reason enough.

The moon phase compatibility chart

Pick your two moons, or find yours down the side and theirs along the top. Each square is those two moons laid together, with a name, a joke and a question. The eight phases make 36 different pairs, and we’ve drawn every one.

Most of the chart is never, because two moons lit on the same side can’t fill a circle. Pink squares depend on the night: a phase lasts about three and a half days, so the same two names can land a night short or a night over.

• The moon phase compatibility chart

  Your moonNew moonWaxing crescentFirst quarterWaxing gibbousFull moonWaning gibbousLast quarterWaning crescentTheir moonNew moonWaxing crescentFirst quarterWaxing gibbousFull moonWaning gibbousLast quarterWaning crescent

  Waxing crescent + waning gibbousPuzzle PiecesOne has the notes, the other has the speech. The shapes the trend is after. These two close it on some nights of their phases and fall just short on others.What do you think I need that I’d never say?This pair’s entry

  Eight moon phases against eight moon phases. Each square shows the two moons laid together and whether the pair closes into a full moon.

  	New moon	Waxing crescent	First quarter	Waxing gibbous	Full moon	Waning gibbous	Last quarter	Waning crescent
  New moon
  Waxing crescent
  First quarter
  Waxing gibbous
  Full moon
  Waning gibbous
  Last quarter
  Waning crescent

  • Always closes
  • Depends on the night
  • Never closes

All 36 moon phase pairs

Every pair has a name, a joke and a real question to ask each other. These are ours, so they’re for fun, and the question is the useful bit. Each pair has its own link, so you can send someone straight to yours.

• New moon pairs

  • Two SecretsNew moon + new moon · never closesNeither of you has told the other the plan. There are two plans.What are you planning that I don’t know about yet?
  • Head StartNew moon + waxing crescent · never closesOne of you starts it, the other writes it down. Nobody else is told.What have you started lately that you haven’t told anyone about?
  • Secret CommitteeNew moon + first quarter · never closesOne had the idea quietly. The other is already disagreeing with it.When did you last change your mind about me?
  • First and NearlyNew moon + waxing gibbous · never closesOne starts everything, the other nearly finishes it. Nothing is ever done.What did we start together that you’d love to finish?
  • The Whole SkyNew moon + full moon · depends on the nightOne dark, one blazing. Between you, the entire moon.When do you feel most noticed by me?
  • The LectureNew moon + waning gibbous · never closesOne says nothing. The other explains why. It works better than it should.What do you wish I’d ask you about?
  • Clean SlateNew moon + last quarter · never closesOne starts things, the other clears them out. Nothing lasts, nothing piles up.What would you love us to start again from scratch?
  • Night ShiftNew moon + waning crescent · never closesOne is asleep, the other is up to something in the dark.What keeps you up at night that I could help with?

  Waxing crescent pairs

  • Two NotebooksWaxing crescent + waxing crescent · never closesYou’ve both written this down. Compare notebooks, carefully.What’s on your list for us that I don’t know is on your list?
  • Planning CommitteeWaxing crescent + first quarter · never closesOne plan, one objection and a very full afternoon.What’s a plan of ours you secretly disagree with?
  • Almost ThereWaxing crescent + waxing gibbous · never closesOne has the plan, the other has nearly done it. Nobody mention the deadline.What small thing could we do this week that you’d secretly love?
  • The EntourageWaxing crescent + full moon · depends on the nightOne walks in. The other is right behind them with the notes.When did I last make you feel proud to know me?
  • Puzzle PiecesWaxing crescent + waning gibbous · depends on the nightOne has the notes, the other has the speech. The shapes the trend is after.What do you think I need that I’d never say?
  • Spring CleanWaxing crescent + last quarter · never closesOne writes the list. The other actually throws things away.What’s one habit of ours you’d happily throw out?
  • Bedtime StoryWaxing crescent + waning crescent · never closesOne has one more idea. The other is asleep. Say it quietly.What’s the last idea you had that you didn’t tell me?

  First quarter pairs

  • Two RefereesFirst quarter + first quarter · never closesYou have both decided. You both disagree. Bring snacks.What’s the silliest thing we’ve argued about, and who was right?
  • Final DraftFirst quarter + waxing gibbous · never closesOne keeps changing it, the other nearly finished it. Version 14 looks good.What have we gone back and forth on for too long?
  • Front RowFirst quarter + full moon · depends on the nightOne makes the entrance. The other has notes on the entrance.What do I do in a room that you like watching?
  • The DebateFirst quarter + waning gibbous · always closesTwo of you, one topic, no chance of an early night.What have I been right about all along?
  • Half and HalfFirst quarter + last quarter · depends on the nightTwo halves, facing each other. Both right. Neither backing down.What have you given way on for me that I never noticed?
  • Sleep On ItFirst quarter + waning crescent · never closesOne wants it settled tonight. The other is already snoring.What do you want settled between us, and what can wait?

  Waxing gibbous pairs

  • Nearly ReadyWaxing gibbous + waxing gibbous · never closesTwo moons nearly full, and two people nearly ready to leave the house.What are you nearly ready to tell me?
  • Fashionably LateWaxing gibbous + full moon · depends on the nightOne is nearly there. The other got there an hour ago and made friends.What are you close to that I should be cheering for?
  • Bright SideWaxing gibbous + waning gibbous · always closesThe brightest nights of the month, one each side of the peak. Loud house.Which week this year would you live again, and why that one?
  • The Last BitWaxing gibbous + last quarter · always closesOne is nearly done. The other has already started throwing it away.What are you ready to let go of this year?
  • Five More MinutesWaxing gibbous + waning crescent · depends on the nightOne is nearly ready. The other is nearly awake.At the end of a long day, what do you want from me: talk, quiet or snacks?

  Full moon pairs

  • Two Full MoonsFull moon + full moon · depends on the nightBoth of you, fully on, in one room. Someone should warn the room.Who are you when nobody’s watching, and do I get to see it?
  • The AfterpartyFull moon + waning gibbous · depends on the nightOne is the party. The other is telling everyone how it went.Which story about us do you tell best, and which bit do you change?
  • Morning AfterFull moon + last quarter · depends on the nightOne brings the party. The other brings the bin bags.Which night of ours would you tell a stranger about?
  • The CurtainsFull moon + waning crescent · depends on the nightOne lights up the room. The other would like it dark. Negotiate.When do you need me loud, and when do you need me quiet?

  Waning gibbous pairs

  • Two ExpertsWaning gibbous + waning gibbous · never closesYou both have an explanation. Neither of you asked.What have I explained to you that you were too polite to say you didn’t get?
  • Long StoryWaning gibbous + last quarter · never closesOne is explaining why the other shouldn’t have thrown it out.What’s a story about your life you’re ready to stop telling?
  • Still TalkingWaning gibbous + waning crescent · never closesOne is still talking. The other stopped listening at nine, happily.What did you tell me lately that I should have listened to properly?

  Last quarter pairs

  • Empty CupboardsLast quarter + last quarter · never closesTwo people clearing out at once. Check the bin before it goes.What do you keep that you could never explain to a stranger?
  • Early NightLast quarter + waning crescent · never closesOne tidied up, the other went to bed. The month is nearly over. You’re fine.What should we quietly stop doing next year?

  Waning crescent pairs

  • Do Not DisturbWaning crescent + waning crescent · never closesBoth asleep. A perfect relationship, as far as anyone can tell.What does a perfect do-nothing day look like, hour by hour?

Which moon phases are compatible?

In the trend, a match is any two moons that fill the circle when you lay them together. Three pairs do it every time: first quarter with waning gibbous, waxing gibbous with waning gibbous, and waxing gibbous with last quarter. Their lit sides overlap enough to leave no gap on any night of those phases.

Eleven more can do it depending on the night: the four opposite pairs below, and any pair with a full moon in it. The other 22 pairs never close.

Opposite moon phases

Opposite phases sit half a month apart: new with full, waxing crescent with waning gibbous, first quarter with last quarter, waxing gibbous with waning crescent. Each is the other’s exact missing shape at the middle of its phase, which is why they’re the pairs people call perfect.

On real birthdays they close only about half the time. New and full does it about 4 times in 10, the others about 5 in 10. When they miss, it’s by a night or two: a thin strip of dark down the seam. That’s why the game counts nights and doesn’t stop at the name of the phase.

Same moon phase: are you a match?

The overlay test says the opposite. Two moons of the same phase are nearly the same shape, so laying them together leaves the dark exactly where it was. Two new moons is about 15 nights short, the widest gap there is.

The one exception is two full moons, which can close it on their own. Our names for the same-phase pairs include Two Notebooks, Two Referees and Do Not Disturb.

How many couples actually pass?

Fewer than half, more than you’d think. You’ll often read one in eight, because there are eight phases and one is your opposite. That counts phase names. Count moons, night by night, and it’s about two in seven: birthdays that overlap past the half-month close too, and a birthday on the very night of a full moon closes with anybody.

• About 2 pairs in 7

  Outcome	How often
  Perfect fit: closes, under a night of overlap	1 in 29
  Closes, with overlap	1 in 4
  One night short	1 in 9
  2 or 3 nights short	1 in 6
  4 to 9 nights short	1 in 3
  10 nights short or more	1 in 11

  How we counted: every day from 1960 to 2009, 18,263 dates, each laid against every 11th date. That’s 30,334,843 pairs, and 8,640,113 of them closed. The dates are spread evenly, so it’s the sum of how the moon works, not a count of real couples.

What moon phase was I born under?

The fields at the top of this page will tell you: one birthday is enough, and the answer shows up right under the moons. The moon goes through its phases about every 29.5 days, so any date falls somewhere in the cycle.

Strictly, the new moon, first quarter, full moon and last quarter are single moments, and the crescents and gibbous moons are the days in between. Here each of the eight gets the same share of the month, so every birthday has a name. Astrology has read these eight as personality types for decades, usually following Dane Rudhyar’s The Lunation Cycle. Below is one plain line of that tradition for each, next to the personality we made up, which is entirely a joke.

• New moonIn tradition: new beginnings, acting on instinct before anyone can see it.In our game: Starts things. Tells nobody.
• Waxing crescentIn tradition: building, loyal to what has just been started and pushing it on.In our game: Has a plan and a slightly too small notebook.
• First quarterIn tradition: decision, pressure, change and getting things moving.In our game: Decides, then argues with the decision.
• Waxing gibbousIn tradition: refining, hard work towards something that matters.In our game: Nearly finished. Always. Forever.
• Full moonIn tradition: being seen, culmination, expression and other people.In our game: Everyone in the room knows they’re here.
• Waning gibbousIn tradition: passing it on, an old soul who shares what they have learned.In our game: Will explain it to you, whether or not you asked.
• Last quarterIn tradition: letting go, independence, reassessing and clearing out.In our game: Clears the cupboards, emotionally.
• Waning crescentIn tradition: completion, wisdom, rest and getting ready for the next cycle.In our game: Is asleep. Do not disturb.

Born on a full moon?

In the trend, full moon birthdays are stuck: your moon is already whole, so there’s nothing to fit. We see it the other way round. If your birthday falls on the night of a full moon, you fill the circle with anybody at all, which either makes you very compatible or means you’ve been doing all the work.

That’s only the night itself. The days either side still count as a full moon by name, but they have a sliver of dark, and they can miss by a night.

When does your birthday moon come back?

Your own moon is in the sky once a month, and the game tells you the next night and can put it in your calendar. Getting it on your actual birthday is rarer. The moon’s phases and the calendar nearly line up every 19 years, a pattern known as the Metonic cycle, so around your 19th, 38th and 57th birthdays you see close to the moon you were born under.

Why does the moon look flipped where I live?

The phase is the same all over the world on a given night, but which side looks lit depends on where you stand. Our drawings show the northern view, with a waxing moon lit on the right. From the southern hemisphere the same moon looks mirrored. It makes no difference to the test.

How the calculator works

We work out how far the moon is from the sun at midday UTC on your birthday, using the series in Jean Meeus’s Astronomical Algorithms. Checked against seven published new and full moons from 1982 to 2024, it lands within half an hour. A birthday has no hour, so we treat a moon within half a night of full as full that night.

Then we lay one moon on the other. If both are lit on the same side, the fuller one is all there is. If they’re lit on opposite sides, the gap is how far their ages fall short of half a month. Either way, that’s the number of nights short. New moon to full takes about 15 nights, which is why a wide gap can reach 15.

• 1. Jean Meeus, Astronomical Algorithms (2nd edition, 1998), chapter 48, for the moon’s elongation from the sun.
  2. Know Your Meme on the earliest video and the March 2023 template, and NBC News on the trend at its peak.
  3. Britannica on the 19-year Metonic cycle.
  4. Dane Rudhyar, The Lunation Cycle (1967), the usual source of the eight phase types in astrology.

If you want to actually know

A moon can’t tell you whether you’re a good match. A good question can tell you a lot more about someone, which is why every pair of moons here comes with four to ask tonight. The couples test on this site goes further: two people answer the same questions, then see where they differ.

Questions people ask