Lunar Calendar

How to Read the Lunar Calendar

The calendar shows a full month at a glance with a moon-phase symbol on every day. Use the arrows to move between months, or tap any date to see its details: the phase name, the moon age (days elapsed since the last new moon), the illumination percentage (how much of the visible disc is lit), and the dates of the next full moon and next new moon. The Today button jumps back to the current date.

The Eight Phases of the Lunar Cycle

One complete cycle — a synodic month — averages 29.53 days and passes through eight named phases:

1. New Moon (0% lit): the Moon sits between Earth and Sun; invisible in the night sky.
2. Waxing Crescent: a thin sliver grows on the right side (Northern Hemisphere view).
3. First Quarter (50% lit): about 7.4 days into the cycle; the right half is illuminated.
4. Waxing Gibbous: more than half lit and still growing.
5. Full Moon (100% lit): about 14.8 days in; rises near sunset and sets near sunrise.
6. Waning Gibbous: illumination begins to shrink after full.
7. Last Quarter: about 22.1 days in; the left half is lit.
8. Waning Crescent: a shrinking sliver before the cycle restarts at new moon.

Because 29.53 days is shorter than most calendar months, the full moon lands about one day earlier each successive month — and occasionally a single calendar month contains two full moons, the second popularly called a blue moon, which happens roughly every 2.7 years.

What Moon Age and Illumination Mean

Moon age counts days from the most recent new moon: age 0 is new, roughly 7.4 is first quarter, 14.8 is full, and 22.1 is last quarter. Illumination is the fraction of the Moon's Earth-facing disc currently in sunlight. The two are linked but not linear — illumination changes fastest around the quarter phases and slowest near new and full moon, which is why the Moon appears "full" for two or three nights in a row.

Practical Uses for a Lunar Calendar

• Astrophotography and stargazing: plan deep-sky sessions around the new moon, when skies are darkest, and moon shots around the full moon.
• Fishing and tides: spring tides (the largest tidal ranges) occur near new and full moons, when Sun and Moon pull in line.
• Religious and cultural dates: Ramadan, Easter, Chinese New Year, and many festivals are set by lunar observations or lunisolar rules.
• Gardening: traditional lunar gardening schedules planting by phase — not scientifically proven, but the calendar makes following it easy.
• Night hiking and outdoor events: a full moon provides usable natural light all night; a new moon means true darkness.

The phases shown are computed from the average synodic period measured from a known new moon, which keeps the calendar accurate to within a few hours over many years — ample precision for planning. For phase details of one specific date, our Moon Phase Calculator offers a focused view.