Moon Phase Calculator
Calculate the exact moon phase, illumination percentage, and lunar day for any date.
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How to use this calculator
- 1
Enter the date you want to check — past, present, or future.
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The calculator shows the moon phase name, an emoji representation, and illumination percentage.
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Lunar day tells you which day of the lunar month this falls on (day 1 = new moon, day 15 = full moon).
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Use the days-until figures for planning moon rituals or gardening by the lunar calendar.
Frequently asked questions
What is a synodic period?
The synodic period is the time between two identical moon phases as seen from Earth — for example, new moon to new moon. It is 29.530589 days. This differs from the sidereal month (27.32 days, the time for the Moon to return to the same position relative to the stars) because Earth is also moving around the Sun while the Moon orbits Earth.
How accurate is this calculator?
This calculator uses the known synodic period from a verified reference new moon (January 6, 2000). Accuracy is within ±1 day for most dates. For precise new moon and full moon timing to the minute, use the USNO Astronomical Applications or NASA's eclipse website, which account for Moon orbital eccentricity.
What is the significance of moon phases in astrology?
In astrology, the new moon is associated with new beginnings and intention-setting, the waxing phases with growth and building, the full moon with culmination and release, and the waning phases with reflection and letting go. Many practitioners align important actions — starting projects, completing them, releasing habits — with corresponding lunar phases.
Moon Phase Calculator — Phase, Illumination & Lunar Day
The eight phases of the moon
The lunar cycle has eight named phases: New Moon (0% illuminated), Waxing Crescent, First Quarter (50%), Waxing Gibbous, Full Moon (100%), Waning Gibbous, Last Quarter (50%), and Waning Crescent. Each phase represents a different relationship between the Sun, Moon, and Earth, producing the characteristic illuminated shapes visible from the surface.
Lunar gardening and the moon calendar
Biodynamic and lunar gardening traditions use moon phases to time planting, pruning, and harvesting. The general principle is: plant crops grown above ground during the waxing moon (new moon to full moon) and root crops or do pruning during the waning moon. While scientific evidence for lunar gardening effects is limited, the practice provides a structured rhythm for garden planning and has been followed across cultures for thousands of years.
Learn more from an authoritative source:
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Results are estimates for informational purposes only and do not constitute professional financial, medical, legal, or technical advice. Read full disclaimer →