See the moon phase, percent lit, moon age and the next full and new moon for today or any date from 1900 to 2100.
The moon phase for a date is worked out from the angle between the Sun and the Moon as seen from Earth, which sets how much of the lit half faces us. This page uses the series published by Jean Meeus in Astronomical Algorithms, chapter 49, to get the exact times of every new moon, first quarter, full moon and last quarter, and chapter 48 to get the share of the disc that is lit. The moon age is the time since the last new moon. The average gap between new moons is 29.53 days, but a real month runs between about 29.3 and 29.8 days, so the age on a given day is a measured value, not a fixed table. For example, the new moon of 8 April 2024 was at 18:21 UTC, and the full moon of 14 March 2025 was at 06:55 UTC. The page reproduces both.
A lunar cycle is split into eight named phases: new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, last quarter and waning crescent. Waxing means the lit part is growing, and waning means it is shrinking. The four main phases are single moments, so the page calls a time a new, quarter or full moon only when it falls within about half a day of the exact moment, which is 6 degrees of the angle. At the first and last quarter the Moon looks half lit, but the lit share is about 50%, because a quarter is a quarter of the cycle, not a quarter of the disc. The drawing on the page shows the lit side on the right when waxing, as seen from the Northern Hemisphere.
Phase times follow Meeus' series and are rounded to the minute. They are converted to clock time with NASA's Delta T polynomials, the difference between the uniform time used in astronomy and clock time, using every era from 1900 to 2150. Checked against NASA's published phase tables for new moons in 1900, 1920, 1961, 2060 and 2100, the times agree within 1.5 minutes. Later years rest on a predicted Delta T, so treat far-future minutes as approximate. The percent lit uses Meeus' short formula, which is within about 0.3 percentage points of his full method in his worked example, so it is shown as a whole number. Dates are in UTC, not your local time. The Moon is the same everywhere at one moment, but a full moon at 23:30 UTC is already the next day in Tokyo, so your calendar date can differ by one. The tool does not give moonrise, moonset or the Moon's position in the sky.
People look up a past date to see the moon on a birthday or a wedding day, and a future date to plan a night shoot, a camping trip or a tide-sensitive outing. Photographers often want the days around a full moon for a bright landscape or the days around a new moon for a dark sky. Tides are highest near full and new moon, called spring tides, which are about every 14.77 days. Gardening calendars that sow by the moon are tradition, not science, and this page makes no claim about them. Type a date from 1900 to 2100, add a UTC time if you know it, and the result updates as you type. Nothing you type leaves your browser.
Leave the date empty and the page uses today's date at 12:00 UTC. It shows the phase name, the percent lit, such as 91%, and the moon age in days. Change the time field if you want the phase for another hour.
The average synodic month is 29.53 days, from one new moon to the next. A single month can be as short as about 29.3 days or as long as about 29.8 days, so the page uses the real new moon times, not a fixed 29.53-day count.
Type your birth date, with a UTC time if you know it. Any date from 1900 to 2100 works. For 21 January 2000, for example, the page shows a full moon at 04:40 UTC that day.
It is the time since the last new moon, in days, from the exact new moon time. A full moon is about 14.8 days old, give or take a day, and the age never reaches 29.8 days because the next new moon starts it again.
The quarter in the name means a quarter of the way around the cycle, not a quarter of the disc. At that point the Sun-Moon angle is 90 degrees, so half the visible disc is lit, which is the lit fraction of 50%.
They follow the Meeus series, tested to agree with NASA's phase tables within 1.5 minutes for sample new moons from 1900 to 2100, and are shown in UTC to the minute. The 8 April 2024 new moon, for instance, is at 18:21 UTC. Nothing is sent to a server; the maths runs in your tab.