Khmer Lunar Date Converter

This converter turns a normal (Gregorian) date into the traditional Khmer lunar date, the way it is written on Cambodian calendars, wedding invitations and pagoda notices. It opens on today and shows the full Khmer sentence, for example ថ្ងៃពុធ ១៥កើត ខែកក្ដិក ឆ្នាំម្សាញ់ សប្តស័ក ព.ស.២៥៦៩, together with the waxing (កើត) or waning (រោច) day, the lunar month, the animal year, the sak, the Buddhist Era year and whether the day is a Buddhist holy day (ថ្ងៃសីល).

Pick any other date to look up a birthday, a ceremony date or a historical event. The calculation uses the traditional Khmer astronomical rules (aharkun, avoman and bodithey) with leap months and leap days, ported from the Kode4U Khmer Calendar app, and it runs entirely in your browser. The calendar covers every day from 1 January 1900 to 31 December 2100.

How to use the Khmer Lunar Date tool

1. The tool opens on today. Use the date picker to choose another day, or step with Previous day and Next day.
2. Read the Khmer lunar day in large type, such as ថ្ងៃ៥កើត, and the full Khmer date sentence below it.
3. Check the boxes for the lunar month, animal year, sak and Buddhist Era year.
4. Look for the Holy day badge and the list of holidays and observances on that date.
5. Press Copy Khmer date to paste the sentence into a message, invitation or document.

Why use ToolOrca Khmer Lunar Date

• Full Khmer lunar date sentence with weekday
• Kert (waxing) and roch (waning) day in Khmer numerals
• Lunar month, including the leap months បឋមាសាឍ and ទុតិយាសាឍ
• Animal year, sak and Buddhist Era (ព.ស.) year
• Buddhist holy days (ថ្ងៃសីល) marked
• Public holidays and observances for the date
• Works offline after loading, no sign-up

How the Khmer lunar calendar works

The Khmer calendar (ចន្ទគតិ, "moon reckoning") counts days by the phases of the moon. Each lunar month starts at the new moon and is split into two halves: kert (កើត), the waxing half, which always has 15 days, and roch (រោច), the waning half, which has 14 or 15 days. Months therefore alternate between 29 and 30 days.

Because twelve lunar months are about 11 days shorter than a solar year, an extra month is added in some years: the month of អាសាឍ is doubled into បឋមាសាឍ and ទុតិយាសាឍ. In other years one day is added to the month of ជេស្ឋ. The tool works these leap months and leap days out with the traditional formulas, so dates match printed Cambodian calendars.

Animal year, sak and Buddhist Era

A Khmer date names three kinds of year. The animal year follows a 12-year cycle (Rat ជូត, Ox ឆ្លូវ, Tiger ខាល … Pig កុរ) and changes at Khmer New Year in mid-April. The sak (ស័ក) follows a 10-year cycle from ឯកស័ក to សំរឹទ្ធិស័ក and also changes at New Year. The Buddhist Era year (ព.ស.) is 543 or 544 more than the Gregorian year and changes on Visak Bochea, the full moon of ពិសាខ.

So a date in early May can still be in the old Buddhist Era year but already in the new animal year. The converter applies each change on the right day.

Buddhist holy days (ថ្ងៃសីល)

Holy days fall on the 8th and 15th day of kert and on the 8th and last day of roch (14 or 15). On these days many Cambodians go to the pagoda, keep the precepts and avoid killing animals. Our Khmer calendar marks every holy day of the month at a glance.