Moon Phase Calculator

Find the moon phase, illumination, moon age and distance for any date. Includes an orbit diagram, lunar calendar, seasonal moon names and supermoon detection. Free, private and no sign-up.

What is a free moon phase calculator online?

A free moon phase calculator online is a tool that tells you the current phase of the Moon, how much of it is illuminated, its age in days since the last new moon, and the dates of the next new moon, first quarter, full moon and last quarter. Astronomers, photographers, gardeners, fishermen and hobbyists have tracked lunar phases for thousands of years — this modern version computes them instantly for any past or future date.

This moon phase calculator runs entirely in your browser. No API calls, no external services, no tracking. Your date selections never leave your device.

How to use this free moon phase calculator online

1. Pick any date — today, your birthday, a future trip or a historical date.
2. Read the phase name, moon age and illumination percentage.
3. Study the orbit diagram to understand why the Moon looks the way it does.
4. See where you are in the 8-phase cycle on the phase strip.
5. Scroll down for the lunar calendar and the next phase countdown.
6. Read the seasonal moon name, moon zodiac sign and activity guidance.

The eight moon phases explained

The lunar cycle passes through eight named phases. The four primary phases are the anchor points:

• New Moon — the Moon is between Earth and the Sun, so the side facing Earth is dark.
• First Quarter — the right half of the Moon (in the Northern Hemisphere) is illuminated.
• Full Moon — the entire face of the Moon is illuminated.
• Last Quarter — the left half is illuminated.

The four intermediate phases are the Waxing Crescent, Waxing Gibbous, Waning Gibbous and Waning Crescent. "Waxing" means growing; "waning" means shrinking.

Understanding the orbit diagram

The orbit diagram above shows a top-down view of the Earth–Moon–Sun system, as seen from above the North Pole. The Sun is far to the left. Earth is in the center. The Moon travels counterclockwise around Earth over about 29.5 days.

Half of the Moon is always lit by the Sun — the half facing the Sun. What we see from Earth depends on where the Moon is in its orbit:

• New Moon: the Moon sits between Earth and Sun, so the lit side faces away from us. We see nothing.
• First Quarter: the Moon is a quarter of the way around. We see half of the lit side.
• Full Moon: the Moon is on the opposite side of Earth from the Sun, so the lit side faces us completely.
• Last Quarter: the Moon is three quarters around, and we see the other half of the lit side.

This is why the phase changes gradually over a month rather than all at once.

Moon age, illumination and distance

• Moon age — days since the most recent new moon (0 to about 29.5).
• Illumination — percentage of the visible disc that is lit (0% at new moon, 100% at full moon).
• Moon–Earth distance — varies from about 356,500 km at perigee to 406,700 km at apogee, averaging 384,400 km.

Supermoon, micromoon and blue moon

Supermoon: a full moon occurring near perigee — the Moon looks up to 14% larger and 30% brighter.

Micromoon: a full moon occurring near apogee — the Moon appears smaller and dimmer than usual.

Blue moon: traditionally the second full moon within a single calendar month, roughly every 2–3 years.

Full moon names by month

Practical uses for moon phase tracking

Astrophotography and stargazing

New moon nights are best for deep-sky astrophotography because the Moon is invisible and does not wash out faint stars. Full moon nights are best for observing the Moon's own surface features.

Fishing and hunting

Traditional wisdom ties fishing and hunting success to lunar phase. The two days around new and full moons are often described as peak feeding times.

Gardening and biodynamic planting

Traditional gardeners plant above-ground crops during the waxing moon and root crops during the waning moon.

Photography and events

Planning a wedding, photoshoot or night hike? Check the phase to know whether to expect moonlight or darkness.

Frequently asked questions