Astronomy Calculator

Moon Phase Calculator

Find the current moon phase or calculate the phase for any date. See upcoming full moons, new moons, and plan your activities around the lunar cycle.

Select Date

Upcoming Moon Phases

Moon Phase Guide

🌑

New Moon

Moon is not visible from Earth

Best for: Stargazing, starting new projects

🌒

Waxing Crescent

Moon is growing, small sliver visible

Best for: Setting intentions, planning

🌓

First Quarter

Right half is illuminated

Best for: Taking action, decision making

🌔

Waxing Gibbous

More than half illuminated, still growing

Best for: Refinement, adjustments

🌕

Full Moon

Fully illuminated

Best for: Completion, celebration, reflection

🌖

Waning Gibbous

Starting to shrink from right side

Best for: Gratitude, sharing knowledge

🌗

Last Quarter

Left half is illuminated

Best for: Letting go, forgiveness

🌘

Waning Crescent

Small sliver remaining on left

Best for: Rest, surrender, preparation

Understanding the Lunar Cycle

29.5 Day Cycle

The lunar cycle (synodic month) lasts approximately 29.53 days. This is the time from one new moon to the next, as the Moon orbits Earth.

Illumination

The Moon doesn't produce light, it reflects sunlight. What we see as phases is simply different portions of the illuminated side visible from Earth.

Tidal Effects

The Moon's gravity causes ocean tides. Spring tides (highest) occur during full and new moons. Neap tides (lowest) happen during quarter phases.

How is Moon Phase Calculated?

This calculator searches for the actual new moon preceding the selected date and measures the elapsed time from there, rather than stepping through a fixed 29.53-day average cycle. Real lunar months run a few hours either side of that average, so anchoring to the true new moon keeps the phase accurate across the year.

Note: Moon phases are calculated for 12:00 noon on the selected date. Actual phase transitions occur at specific times that vary by time zone.

Track Moon Phases in WeatherAI

WeatherAI shows current moon phase, illumination percentage, and moonrise/moonset times alongside your daily weather forecast.

Free to download • No credit card required

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