How to use it
- Type the year you want, from 2020 to 2035, or leave the box empty for this year.
- Read the table in date order. Each row is one phase, with its exact moment and the sign the Moon is in.
- Look at the blue moon line to see whether the year has an extra full moon in one month.
- Tick Show times in UTC if you want Universal Time.
How the phases are defined
The phases follow the difference between the Moon's and the Sun's ecliptic longitudes, seen from the Earth. A new moon is at 0 degrees, a first quarter at 90, a full moon at 180 and a last quarter at 270. These are the definitions used by the US Naval Observatory.
The times are computed by astronomy-engine (MIT), which searches for each exact moment, and they agree with the US Naval Observatory's published phase times to within about a minute.
phase = Moon's longitude − Sun's longitude (degrees, 0 to 360)
0 new moon · 90 first quarter · 180 full moon · 270 last quarterBlue moons and the calendar
The name blue moon is used for the second full moon of one calendar month. A month has at most two full moons, so a blue moon happens about once every two or three years. The calendar counts months in the time zone shown on the page, so the same full moon can be a blue moon in one zone and not in another when it falls near midnight.
What is not included
- Supermoons. Their definition depends on a distance rule, so they are not marked here.
- Whether the Moon is visible at a given time from your town. The moon rises and sets at different times everywhere.
Worked example: the phases of January and May 2026
The new moon of 18 January 2026 is at 19:52 UT, when the Moon is in Capricorn. The first quarter follows on 26 January at 04:47 UT, in Taurus.
In May 2026 two full moons fall in one month: on 1 May 2026 at 17:23 UT and on 31 May 2026 at 08:45 UT. The second is the blue moon of the year, so the 2026 calendar lists 13 full moons.
Frequently asked questions
How many full moons are there in a year?
Usually twelve, because a lunar month is about 29.5 days. A year with thirteen full moons has one blue moon, which happens when two full moons fall in the same calendar month.
Is a blue moon blue?
No, the Moon looks normal in colour. The name is only a term for the second full moon of a month, and very rarely a smoke or dust event turns the Moon bluish.
What is the difference between a quarter moon and a half moon?
They are the same thing. A quarter moon is half lit, and the first and last quarters are the moments when the Sun and Moon are 90 degrees apart in longitude.
Why do the times differ from the times for my own town?
The phases happen at one moment worldwide. Only the clock time changes with your time zone, which the table shows with its name.
Sources
- US Naval Observatory: Phases of the Moon, the phase times used to check this calendar
- astronomy-engine, the open-source astronomy library (MIT) that computes the phases
Figures and text last checked on Tuesday, November 10, 2026.