Birthday Moon Phase Calculator

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Everyone knows their Sun sign. Far fewer know what the Moon was doing the day they were born.

Enter your birth date and MoonX gives you the exact phase, the sign the Moon was travelling through and the lunar day you were born into. Readings are written by MoonX astrologers.

Your birth time is optional: it makes the result exact to the minute and settles your Moon sign on days when the Moon changed sign.

We don't store or publish your birth details. They're used for this calculation only.

The three things we calculate

Moon phase

The shape of the Moon on your birth day — from a thin crescent to a full disc — and its exact illumination. It's the part that's gone viral as the "moon phase soulmate" trend, but the number we show is the real illuminated fraction, not a rounded-off picture.

Moon sign

The zodiac sign the Moon was travelling through. The Moon moves about 13° a day and changes sign roughly every two and a half days, so your Moon sign can easily differ from a friend born the same week — and it describes your emotional nature rather than your outward one.

Lunar day

Which day of the lunar month you were born into, counted from the previous new Moon. It's an older way of marking time than the twelve-sign zodiac, and each of the roughly thirty lunar days carries its own character.

What Your Birth Moon Phase Says About You

What your birth Moon says about you starts with a simple idea: your Sun sign is how you present yourself, while the Moon's phase the moment you were born marks where in the cycle you began — your emotional tempo. New-Moon people start from zero and push forward; full-Moon people live in constant culmination and contrast. Below is each moon-phase personality in short, with famous people born under each Moon phase for comparison.

Phase	Illumination	What it says about you	Born under this Moon
New Moon· 0–4%	0–4%	A starter who decides on instinct and would rather begin than wait for the full picture. You meet conflict head-on and forget it fast. Waiting, or joining something half-built, is what drains you.	Blake Lively · Aug 25, 1987 · actor Scarlett Johansson · Nov 22, 1984 · actor Emma Chamberlain · May 22, 2001 · content creator
Waxing Crescent· 4–31%	4–31%	You decide in bursts of enthusiasm and need something to push against. You'll fight for an idea you believe in, then lose steam once the novelty fades. Repetition and unfinished starts wear you down.	Rihanna · Feb 20, 1988 · singer Billie Eilish · Dec 18, 2001 · singer Ryan Gosling · Nov 12, 1980 · actor
First Quarter· 31–69%	31–69%	A decider under pressure, at your best with a problem to solve or an obstacle to push through. Conflict doesn't rattle you; drift does. A vague situation with no clear next step drains you fastest.	Ariana Grande · Jun 26, 1993 · singer Natalie Portman · Jun 9, 1981 · actor Austin Butler · Aug 17, 1991 · actor
Waxing Gibbous· 69–96%	69–96%	You refine rather than launch, deciding after analysis and some second-guessing. Conflict you handle by fixing and improving, not walking away. “Good enough,” and being rushed before you're ready, is what exhausts you.	Kendall Jenner · Nov 3, 1995 · model Lizzo · Apr 27, 1988 · singer Lily Collins · Mar 18, 1989 · actor
Full Moon· 96–100%	96–100%	Life runs on culmination — everything heightened, and you know yourself through other people. You decide emotionally and out loud, and can't hide how you feel. Constant intensity, and pressure to pick sides, drains you.	Tom Holland · Jun 1, 1996 · actor Kristen Stewart · Apr 9, 1990 · actor Megan Thee Stallion · Feb 15, 1995 · rapper
Waning Gibbous· 96–69%	96–69%	The explainer: you decide by talking things through and turning experience into something to pass on. Conflict you'd rather resolve with words than force. Being unheard, or told to keep quiet, tires you out.	Zendaya · Sep 1, 1996 · actor Olivia Rodrigo · Feb 20, 2003 · singer Adele · May 5, 1988 · singer
Last Quarter· 69–31%	69–31%	A reformer's streak: you decide by questioning what others take for granted, and hold your ground on principle. Going through the motions on something you've stopped believing in is what drains you.	Selena Gomez · Jul 22, 1992 · singer Zoë Kravitz · Dec 1, 1988 · actor Chappell Roan · Feb 19, 1998 · singer
Waning Crescent· 31–4%	31–4%	Born in the cycle's closing stretch, you decide slowly and inwardly and need real solitude to recharge. You avoid open conflict, processing it privately. Crowds, noise and back-to-back demands empty your tank.	Dua Lipa · Aug 22, 1995 · singer Emma Stone · Nov 6, 1988 · actor Bella Hadid · Oct 9, 1996 · model

Phases calculated from each person's publicly documented birth date.

Moon phase or Moon sign — they're not the same thing

These two get mixed up constantly, but they measure different things. Your Moon phase is how the Moon looked — how much of its face was illuminated by the Sun, anywhere from new to full. Your Moon sign is where the Moon was against the backdrop of the zodiac. One is about appearance, the other about position, and they change at completely different speeds: the phase cycles over about 29.5 days, while the sign changes every couple of days.

So two people born hours apart can share a phase but not a sign, or a sign but not a phase. If you came here from the soulmate trend, the phase is the part you want. If you're building a natal chart, it's the sign that matters.

Do I need my exact birth time?

For most of this page, no. The Moon phase and the lunar day barely move over a single day, so your birth date alone pins them down. The Moon sign is unambiguous about six times out of ten — but the Moon changes sign every couple of days, so on the other days it crosses a boundary while you were being born. When that happens we show you both signs and ask which side of the change you arrived on, rather than guessing. If you do know your birth time, it simply makes the result exact to the minute.