Detailed guide
How to use the moon-phase calculator
The four primary lunar phases
At new moon, the Moon is approximately in the Sun’s direction from Earth and is largely invisible at night. The illuminated portion grows toward first quarter, reaches full moon when Earth lies more nearly between Sun and Moon, and decreases again through last quarter.
The table gives the astronomical instant of each primary phase. Waxing and waning intermediate phases occur between these events but do not appear as separate rows.
Step by step
Worked example: Moon phases in August 2026
Find the four primary phases in August 2026 for the Europe/Berlin time zone.
- 1 Last quarter: August 6 at 04:21.
- 2 New Moon: August 12 at 19:36; first quarter: August 20 at 04:46.
- 3 Full Moon: August 28 at 06:18.
Result: the month contains one local instant for each of the four primary phases.
Why local date and time can differ
A lunar phase is one global astronomical moment, yet that instant can fall on different local calendar dates in different time zones. The page uses Europe/Berlin unless the application is configured with another zone.
The service applies astronomical approximations, converts ephemeris time to UTC and then to local time. This is suitable for calendar planning; high-precision scientific work should use specialist ephemerides.
Practical uses for moon-phase dates
Lunar phases help with sky observation, night photography, events and cultural calendars. Nights around new moon are darker without strong moonlight, while full moon brightens the night. Cloud and local light pollution remain important practical factors.
This calendar does not assess broad medical, psychological or gardening claims associated with lunar phases. It provides astronomical dates, not medical or agricultural advice.