How Many Months in the Chinese Lunar Year?

Each of the chinese lunar months is tied to the moon, not to a fixed slot on a printed wall calendar. A month begins on the day of a new moon (朔, shuò) and ends the day before the next new moon. One full lunar cycle is about 29.5 days, so in practice a month is either 29 days long (a “short” month) or 30 days long (a “long” month). There is no fixed pattern of 30 and 31 the way the Gregorian calendar has.

Twelve of these months add up to roughly 354 days. That is about 11 days shorter than the 365-day solar year. Left uncorrected, the lunar calendar would slide backward through the seasons — Chinese New Year would drift out of late winter within a couple of decades. The fix is the leap month, covered next. If you want the deeper mechanics of new moons, solar terms, and how the whole system is stitched together, our Chinese lunar calendar explained guide is the companion read.

The Chinese calendar is lunisolar: it follows the moon for its months but keeps itself anchored to the sun for its seasons. The tool that reconciles the two is the chinese leap month. Roughly every 19 years there are seven leap months — the so-called Metonic cycle — which works out to a leap month about every two to three years.

A leap month is not a brand-new named month. Instead, one of the existing months is repeated. If a leap month follows the fourth month, that year has a fourth month and then a “leap fourth month” (闰四月) before the calendar moves on to the fifth. Which month gets doubled is decided by the position of the 24 solar terms, not by a fixed rule, so the leap month lands in a different spot each cycle. The authoritative public source for these determinations in the Chinese-speaking world is the Hong Kong Observatory's annual Gregorian-Lunar conversion tables, published by Hong Kong's official meteorological authority.

Here are the twelve numbered lunar months with their common Chinese names and the rough Gregorian window each one falls into. Because the lunar calendar drifts against the solar one, the Gregorian span shifts by a couple of weeks from year to year — treat these as approximate.

In a leap year, a repeated month is inserted somewhere in this list — for example a “leap fourth month” would sit between the 4th and 5th rows.

This is the table most people actually come here for. It lists which recent and upcoming Chinese years carry a 13th month and which month gets repeated. Years not listed are ordinary 12-month years — 2026, for instance, has no leap month.

For a fully authoritative year-by-year list, the Wikipedia entry on the Chinese calendar tabulates leap months going back centuries, and it cross-checks against the Hong Kong Observatory almanac cited above.

Here is the practical payoff. The Chinese gender chart is read with two inputs: the mother's lunar age and the lunar conception month. That second input is exactly where the number of months trips people up. If you conceive in, say, mid-July of a leap-sixth-month year, your Gregorian “July” might actually fall inside the leap sixth month rather than the seventh — and the chart row you land on changes accordingly.

So the rule is simple but easy to forget: always convert your conception date to its true lunar month before reading the chart, and check whether a leap month sits in between. Our Chinese conception calendar guide walks through that conversion step by step, and if you are working backward from a last-period date, the Chinese gender calendar by LMP shows how to estimate conception first. To get the other half of the lookup right, the lunar age calculator handles the mother's age, and you can run the full prediction from the Chinese Gender Calendar homepage.