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What moon phase was on your birthday?

Enter the date you were born and we will draw the moon exactly as it stood that night — the phase, the share of the disc that was lit, and the reading that phase has carried in the traditions we work with.

Calculated in your browser. Nothing about your birth date is stored or sent anywhere.

The moon and your cycle

A lunar month is 29.5 days and the average menstrual cycle is close to it — which is why so many traditions read the two together. Your cycle does not have to match the sky to be healthy, and it usually does not. What is useful is the shape they share: a dark beginning, a bright middle, a gradual return. That is the same four-part rhythm we use in our phase guides.

Read the four cycle phases

Beyond the moon

The moon phase on your birthday is one line of a much longer chart. Your free birth chart adds your Western Sun, Moon and Rising signs, your Vedic moon nakshatra and your Chinese Bazi four pillars — still free, still no account.

Get your free birth chart

Questions

How do you work out the moon phase for a past date?
We calculate the angle between the sun and the moon as seen from Earth at that moment, using the same astronomical engine that powers our birth charts, and then draw the disc at its true illumination. It is not a lookup table or an approximation of the 29.5-day average.
Do I need my birth time?
No. The moon's phase changes slowly — roughly 12 degrees a day — so noon on the correct date gives you the right phase. Birth time matters for your Rising sign and your Bazi hour pillar, not for this.
What does the percentage mean?
It is the share of the moon's visible disc that was lit by the sun on that date. Zero per cent is a new moon, 100 per cent is a full moon, and the quarters sit at roughly 50 per cent.
Is my birth moon the same as my moon sign?
No, and they are easy to confuse. The phase is the moon's relationship to the sun. Your moon sign is the constellation the moon stood in. You can see both on the free birth chart.
Is any of this stored?
No. The calculation runs in your browser, and we keep no record of the date you typed. If you later choose to open an account, you decide then what to save.