How to Read a Lunar Calendar: the Day Card Explained

A lunar calendar looks like an ordinary table, but a row in it does not describe a calendar day. It describes an interval of lunar time that has its own number, its own start, its own phase and its own zodiac sign. You can only read a row by taking these quantities apart one at a time.

The six columns and what each means

In the main calendar on lunar.day a day row has six columns: date, lunar day number, day start, phase, zodiac sign and sign-ingress time. The values in them are independent of each other.

Date — the only field anchored to the familiar calendar. Everything else may disagree with it.

Lunar day number — a position in the lunar month, from 1 to 29 or 30. The month is not anchored to the solar cycle: a new-moon month begins at the new moon and runs until the next one.

Day starts — the local time at which that lunar day began. It is there because lunar days run longer than calendar days and so do not “start” at midnight.

Phase, sign and ingress time — three separate fields, each with its own moments in time. Cardinal phases (quarters) change about once every 7.4 days, eighth-parts of the phase about once every 3.7 days, and the sign about once every 2.3 days.

Look at real rows for Moscow in September 2026:

Notice that the number fell from 29 to 1 while the start time moved forward from 04:35 to 06:27. Lunar days run longer than calendar days (why — in the next section), and the accumulated shift is visible in the time column.

Why a lunar day is longer than a day

Lunar days run longer than calendar days because while the Earth makes one turn the Moon moves forward along its orbit: the mean interval between moonrises is 24 / (1 − 1/29.53) ≈ 24.84 hours, that is about 24 hours 50 minutes. This is a monthly mean; on individual days the start-time shift ranges from half an hour to almost two hours (see the article on moonrise and moonset for details).

A practical rule follows from this: the start time of a lunar day cannot be memorised — it has to be read from the table. A usable anchor appears only at the start of the month, at the new moon.

Lunar day and lunar age: not the same thing

These two quantities look alike but answer different questions.

The Moon's age is the astronomical number of days since the new moon. It is always non-negative and accumulates continuously: 0 at the new moon, about 7.4 at the first quarter, about 14.8 at the full moon, about 22.1 at the last quarter.

The lunar day number is a calendar position that resets to 1 after the new moon.

The gap shows in the actual data: the new-moon moment in Moscow on 11 September 2026 is 06:27, while lunar day 1 in the table begins on 12 September at 06:27. That is how lunar.day counts: the day start is tied to the lunar-day grid rather than to the moment of conjunction, so the date of the new moon and the date of the first lunar day differ by roughly a day — the same clock time a day apart.

On the phase page both values are shown separately: the lunar day number in the table, the age underneath it on its own line.

Why the zodiac sign changes faster than the phase

The Moon's phase completes a full cycle in 29.53 days and divides into eight parts — about 3.7 days per phase. The Moon passes through the zodiac in 27.3 days, which divides into twelve parts — about 2.3 days per sign. So within one 3.7-day phase the sign almost always changes, while within one 2.3-day sign the phase changes only in about two cases out of three.

The main consequence is: phase and sign cannot be derived from one another. No rule of the form “at the full moon the Moon is always in such-and-such sign” works. A full moon falls about 180° from the Sun, and the sign it occupies shifts from month to month.

In the table the sign is shown for the whole interval, and the ingress time is filled in only on the day the ingress happened. An empty cell means “the sign did not change on that day”, not “no data”.

How to read the specialty calendars

The specialty calendars — hair, gardening and timber — take only the zodiac sign from the main table and, for timber, the lunar day number. Everything else they ignore.

Timber is the only one that uses two fields at once. In its tradition the first half of the month counts as waxing (days numbered 1 to 15): on such days the rating is lowered by one step regardless of the sign.

And separately: the rules of these calendars are tradition, not measurement. No haircut, no sowing and no felling becomes lucky or unlucky because of the Moon's phase. The calculator shows what the tradition claims, and nothing more. Three articles work through this in detail together with the rating tables: hair calendar, gardening calendar, timber calendar.

How to view the calendar on lunar.day

Pick a city — the calendar is computed for its coordinates and time zone. The lunar day start time depends on the city's coordinates, while the sign-ingress time is a geocentric moment, the same worldwide: in the table it is simply recalculated into the local zone. The current month is shown by default and the arrows in the heading switch to neighbouring months.

At the bottom of the table each day offers the hair, gardening and timber calendars; they also have their own pages. If you switch the zodiac system, the sign in the main table changes while the ratings in the specialty calendars stay tropical — that is deliberate, because the rules were written against it.

Summing up

A row in a lunar calendar is not a single date but six columns: date, number, day start, phase, sign and ingress time. The lunar day number is counted from the new moon, and it runs slightly longer than a day, so its start time drifts by about an hour to an hour and a half from day to day. The phase and the zodiac sign run on different periods and are never derivable from one another. The specialty calendars take only the sign from the table, and timber also the day number — the only calendar where two rules combine. When reading, start with the “Day starts” column rather than the number: it shows immediately where the boundary between lunar days falls.