Your Moon · Moon phase calculator
Every night has its own moon. Find yours.
Choose a date that matters to you: a birth, a wedding, the night you met. The moonphase disc of the Avanté Lunar turns back to that night and shows the moon as it stood in the sky.
How the moon phase calculator works
The moon needs 29.53 days on average to go from one new moon to the next. Astronomers call this the synodic month. The calculator counts how many of those cycles lie between a known new moon, on 6 January 2000 at 18:14 UTC, and the date you choose, and reads where in the cycle that day falls.
It shows the moon at midday (UTC) on that date. Because the real orbit runs a little faster or slower than the average, the phase is accurate to within about a day. It is the same lunar cycle Eise Eisinga built into his planetarium in Franeker in 1781, and the same one the moonphase disc of the Lunar follows on your wrist.
The eight phases of the moon
- New moon: the moon stands between the earth and the sun and cannot be seen.
- Waxing crescent: a thin edge of light that grows each evening.
- First quarter: half lit, about a week after the new moon.
- Waxing gibbous: more than half lit and still growing.
- Full moon: fully lit, rising as the sun sets.
- Waning gibbous: just past full, the light begins to shrink.
- Last quarter: half lit again, now on the other side.
- Waning crescent: a last thin edge before the next new moon.
A moon that belongs to one date
A calendar date rarely meets the same moon twice. Date and phase line up again only about every 19 years, the Metonic cycle, so the moon over a birth or a wedding belongs to that night. That idea is behind the Avanté Lunar: a real moonphase watch for €180, with the moon turning on the dial every night after. Want to know what the moon is doing right now? See today’s moon phase.
Questions about the moon phase
What moon phase was I born under?
Choose “A birth”, enter your date of birth and the calculator turns back to that night. You see the name of the phase, how much of the moon was lit and which day of the lunar cycle it was.
How accurate is the moon phase calculator?
It works with the average synodic month of 29.530589 days, so the phase is correct to within about a day. For the exact minute of a full or new moon, an astronomical almanac gives more precision.
Is the moon phase the same everywhere on earth?
Yes, the phase on a given date is the same everywhere. South of the equator the moon appears the other way round, so a crescent lit on the right in Europe is lit on the left in Australia.
How do I set the moonphase on my Avanté Lunar?
Check today’s moon on the Live Moonphase page and follow the steps there to turn the disc until it matches the sky.
Can I give someone the moon of their date?
Yes. Save the moon of their date as an image with the button under the card, and give it together with a Lunar. The card keeps the date; the Lunar keeps the moon turning on their wrist.