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Moon phase on your birthday
Find the lunar phase and illuminated fraction at birth, with a clear diagram and a distinction between Moon phase and Moon sign.
The Moon sign and Moon phase answer different questions. A sign is a sector of the zodiac; a phase describes the apparent separation of the Moon and Sun and the illuminated portion of the lunar disc. This calculator shows that geometry for the moment you enter.
No name, email or account is needed. Your details stay on your device. Use the clear button to remove entered details and results.
How to use this tool
Enter a date, local time and time zone. A birthplace is not needed for the geocentric phase. Use the time zone of the recorded event, rather than the time zone where you happen to live now. If you do not know the time, calculate more than one plausible instant and treat a phase boundary cautiously.
How to read the result
The diagram is schematic, with waxing illumination shown on one side and waning illumination on the other. Its orientation is not a simulation of the Moon above your local horizon. The percentage describes illumination; it is not a compatibility rating, a personality measurement or the probability of an outcome.
Method and limits
Results cover 1900–2099. A phase name groups a continuous angle into eight familiar categories, so the displayed name can change close to a category boundary even though the Moon changes continuously. Observing conditions and the Moonrise time require the separate local-sky tool.
The calculation uses Astronomy Engine 2.1.19 and, where applicable, the project’s offline time-scale and house geometry modules. Mathematical positions and traditional interpretation remain separate.Read the full methodology.