Duean Nuea: Why Lanna Months Run Two Months Ahead

Duean nuea ("northern months") is the Lanna way of counting lunar months. The Moradok Lanna dictionary explains it under the word month (duean, เดิอฯร): "the people of Lanna count their months two months ahead of the central Thai". The northern months are therefore a key to reading Lanna traditions, because almost every merit-making festival is dated in "northern months", such as Yi Peng, Tan Kuay Salak or the liang dong spirit feast.

This article introduces the month names, the two ways of naming days, wan meng and wan tai, and the way of naming years called pi hon tai, which the people of Lanna have used since the age of the stone inscriptions.

Why are the northern months two months ahead?

The difference has nothing to do with the moon, because the full-moon days of Lanna and central Thailand always fall on the same day. It lies in where month 1 begins.

The preface of the Lanna Calendar for 2022, compiled by Saknarin Chao-ngio (ศักดิ์นรินทร์ ชาวงิ้ว), explains that in the duean pak lem count "month 1, or duean kiang, begins when the moon becomes full in the new cycle of lunar mansions, around mansion 1–2", and that this is the count "used most widely in Lanna, which is two months ahead of the months of central Thailand".

Since month 1 of Lanna falls in month 11 of central Thailand, every following month stays two months ahead of central Thailand all year round.

Duean kiang and duean yi: the Lanna month names

The first month of Lanna is duean kiang (เดิอฯรกยฯง, duean kiang). The dictionary explains it as "the first month, or duean ai, of the lunar calendar, which is month 11 of central Thailand", and notes that it may also be called duean chiang.

The second month is duean yi (เดิอฯรยี่, duean yi), which is month 12 of central Thailand. From the third month on, the months are called by number: month three, month four, and so on to month twelve.

Kham Mueang (Northern Thai) also has its own words for the waxing and waning halves of each month.

Key dates: northern months against central Thai months

Once you understand the "plus two" rule, the dates of Lanna traditions become much easier to read. Here are examples for 2026–27 from the Moradok Lanna calendar:

Duean pak lem, duean hora and the Tai Lue count

Lanna does not have only one way of counting months. The same 2022 Lanna Calendar explains that there is also duean hora, which "counts month 1 as the month whose full moon falls around lunar mansion 3". It is therefore one month behind duean pak lem and one month ahead of central Thailand.

The compiler states that duean hora is used in communities influenced by Tai Lue–Tai Khuen culture, such as Mae Sai, Chiang Khong, Chiang Kham and northern Nan, matching the count of the Tai Lue of Sipsongpanna and the Tai Khuen of Kengtung. The Moradok Lanna dictionary records the same: "the Tai Lue count one month ahead of the central Thai".

The example above comes from the dictionary's explanation of the word duean. The two counts also affect beliefs: the calendar's compiler points out that when the months are counted differently, the inauspicious days of each month also differ, so that calendar prints both counts side by side.

Wan meng: the seven-day week

Wan meng (วันฯเมังฯ, wan meng) is the count of the days of the week. The dictionary explains it as "the Mon way of counting days, like the Thai count of days", beginning with Sunday as the first day and ending with Saturday, and "some use numbers instead, that is 1 2 3 4 5 6 7".

So inscriptions often say "day 4", meaning Wednesday, which Kham Mueang calls wan put (วันฯพุธ). Kannika Wimonkasem (กรรณิการ์ วิมลเกษม, 2002) explains that Lanna inscriptions call this numbered way of naming the day "wan meng", and that meng is a name for the Mon people.

Wan tai: the 60-day cycle of mae mue and luk mue

Besides wan meng, the people of Lanna have a second system for naming days, called wan tai (วันฯไท, wan tai), which comes from the hon tai count (ห฿นฯไท, hon tai). The dictionary explains that hon tai is "a way of counting time or eras in which the mae mue and luk mue are paired together".

• Mae mue (แม่มื้, "mother days"), also called mae wan (แม่วันฯ), has 10 names: kap, dap, ruai, mueang, poek, kat, kot, ruang, tao, ka.
• Luk mue (ลูกมื้, "child days") has 12 names: chai, pao, yi, mao, si, sai, sa-nga, met, san, rao, set, khai.

They are paired in order: kap chai, dap pao, ruai yi … When the mae mue run out at ka, they start again from kap, but the luk mue carry on, giving kap set, dap khai. This continues until all 60 pairs are complete at ka khai, and then a new cycle begins.

Wan tai in a real calendar

The dictionary gives an example under the word mae pi (แม่ปี, mae pi): Wednesday 22 November 2006 was wan dap mao. Counting on from that day in cycles of 60 days gives the wan tai names of this year's key days:

The same count agrees with the 2022 Lanna Calendar, which gives Saturday 16 April 2022 as "wan tai kat khai" (วันไทกัดใค้), and with the inscription date that Kannika Wimonkasem cites as an example (Wednesday 2 December 1789, "tai poek si", ไทยเปิกสี). This shows that the 60-day cycle has run on without a break from the time of those inscriptions to the present day.

Pi hon tai: the old Tai year names

Pi hon tai (ปีห฿นฯไท, pi hon tai) is the old Tai way of counting and naming years. The dictionary explains that there are two methods:

1. A 12-year cycle following the zodiac, using the names chai, pao, yi, mao, si, sai, sa-nga, met, san, lao, set, khai, which match the years of the Rat, Ox, Tiger and so on to the Pig.
2. A 60-year cycle, pairing the 10 mae pi ("mother years": kap, dap, ruai …) with the 12 luk pi ("child years"), in the same way as wan tai.

The mae pi are easy to remember. Kannika Wimonkasem (2002) explains that the mae pi names "are names that give the last digit of the Chula Sakarat year".

The dictionary's example is CS 1368 (2006 CE), which is the year ruai set (last digit 8 = ruai, Year of the Dog = set). The 2022 Lanna Calendar gives CS 1384 as the year tao yi (last digit 4 = tao, Year of the Tiger = yi). By the same rule, CS 1388, which began in April 2026, is the year ruai sa-nga (Year of the Horse, อัฏฐศก).

Reading dates in Lanna inscriptions

Kannika Wimonkasem (2002) explains that Lanna inscriptions usually begin by giving the era year, the hon tai year name, the month, the wan meng, the wan tai, and even the auspicious moment and the watch of the day. An example is the inscription of Chao Muen Kham Phet (Lampang inscription 1), which opens:

"ศักราชได้ 838 ตัว ในปีรวายสัน เดินยี่ แรม 3 ค่ำ วันพุธ ไทยเปลิกสง้า" — Lampang inscription 1, cited in Kannika Wimonkasem (2002)

["In the era year 838, in the year ruai san, in duean yi, on the 3rd waning day, Wednesday, tai poek sa-nga."]

Read part by part:

• Sakkarat dai 838 tua ("the era has reached 838"): Chula Sakarat 838, which is 1476 CE ("tua" is the classifier for an era year).
• Pi ruai san: the mae pi is ruai because the last digit is 8, and the luk pi san is the Year of the Monkey.
• Duean yi: the northern duean yi, month 12 of central Thailand.
• Wednesday … tai poek sa-nga: gives both the day of the week and the wan tai name.

From a single line, the reader learns the year, the month, the waning day, the day of the week and the wan tai, which helps scholars match the dates in inscriptions to today's calendar precisely.

The Lanna calendar in life today

The Lanna calendar is called pak-kha-tuen lan-na (ปักขฯทืนฯล้านฯนาฯ) in Kham Mueang (from pak-kha-tuen, ปักขฯทืนฯ, "calendar"). The dictionary explains that it is a solar–lunar calendar that shows both the waxing and waning days and the good and bad days according to belief, such as wan kao kong, on which a cremation should not be held, and wan hua riang mon, which is good for a wedding.

Lanna calendars are still compiled and published today, such as the 2022 Lanna Calendar cited above, which follows the kao kong days agreed by the Pakkhathuen Lanna Club (ชมรมปักขทืนล้านนา) and prints both month counts side by side. You can look up the northern-month lunar date of any day on the Moradok Lanna calendar.

Summary

• Duean nuea runs two months ahead of central Thailand because month 1 (duean kiang) falls in central Thai month 11, while the full-moon days still coincide.
• The Tai Lue–Tai Khuen duean hora runs one month ahead of central Thailand: Songkran is month 5 in central Thailand, month 6 for the Tai Lue and month 7 in Lanna.
• Wan meng is the day of the week (1 = Sunday … 7 = Saturday), while wan tai is a 60-day cycle made from 10 mae mue and 12 luk mue.
• Pi hon tai uses mae pi that give the last digit of the Chula Sakarat year, so CS 1388 is the year ruai sa-nga. The year changes on wan pha-ya wan in mid-April.

Look up more Lanna words for days, months and years in the Moradok Lanna dictionary (in Thai), and see how northern-month dates work in real festivals in the articles Tan Kuay Salak and Pu Sae Ya Sae.

Sources

• Moradok Lanna dictionary (in Thai): เดือน · เดือนเกี๋ยง · วันไท · ปีหนไท · แม่ปี
• Moradok Lanna calendar (Calenos): moradoklanna.com/calendar (northern-month lunar dates for 2026–2027)
• กรรณิการ์ วิมลเกษม [Kannika Wimonkasem]. (2002). ศักราช ศก ปี วัน เดือน ฤกษ์ และยามในจารึกล้านนา [Eras, era names, years, days, months, auspicious moments and watches in Lanna inscriptions]. Damrong Wichakan 1(1). Faculty of Archaeology, Silpakorn University. In Thai.
• ศักดิ์นรินทร์ ชาวงิ้ว [Saknarin Chao-ngio]. (2022). ปฏิทินล้านนา พ.ศ. ๒๕๖๕ [Lanna Calendar 2022]. Rajamangala University of Technology Lanna. In Thai.