Enter a date to get the moon age (days since the new moon), the moon phase (new, crescent, first quarter, full, last quarter…) and the illuminated fraction — handy for moon-viewing, fishing, photography, and calendars. Switch modes to compute a baby's age from their birth date: months and days, total days old, plus Japanese celebration milestones (Oshichiya, Omiyamairi, Okuizome/100 days, half birthday, first birthday). Everything runs locally; the dates you enter are never stored or uploaded (only your view-mode preference is saved).
How to use
- In Moon phase mode, pick a date to see the moon age, phase and illumination.
- Switch to Baby age mode and enter the date of birth and the target date.
- Read the age in months/days and the milestone dates.
FAQ
What is moon age?
It's the number of days since the new moon: 0 is new, ~15 is full, and ~29.5 returns to new. This tool approximates with the mean synodic month (29.53 days).
Does it give the exact minute of the full/new moon?
No — it gives a per-date estimate of moon age and phase (computed at noon). It does not resolve the exact instant of new/full moon or location-specific differences.
How is a baby's age counted?
From the birth date, completed months are shown as months and the remainder as days, plus total days/weeks and celebration milestones (Oshichiya = 7 days, Okuizome = 100 days, etc.).
Is the birth date I enter stored?
No. All calculation runs in your browser; dates are never stored or uploaded. Only your view-mode preference is saved on this device.