Days of the Week in Thai, and the Colour Each One Wears

One word plus a planet, seven times

Most vocabulary lists present the Thai days as seven unrelated words to memorise, which is both harder than necessary and slightly false. Every one of them is the same two-part construction: วัน wan, day, followed by the name of a heavenly body borrowed from Sanskrit. Monday is moon-day, Tuesday is Mars-day, Friday is Venus-day. Once you see the seam, you are learning seven short words rather than seven long ones.

Start with วัน itself, because it is three letters and gives you a free win. ว is a w and it is low class, ั is a short a written above it, and น closes the syllable with an n. An n ending is a live ending, there is no tone mark, and low class plus live plus no mark gives mid tone. wan. Everything after that in this post is the second half.

The bonus is that the second halves are also the planets in Thai astronomy. Learn วันอังคาร and you have ดาวอังคาร, Mars. วันพฤหัสบดี gives you Jupiter, วันศุกร์ gives you Venus. Seven day names, seven planets, one set of words.

The seven days, their planets and their colours

Four of those seven are one syllable after วัน, which makes them the shortest real words you will meet outside door signs. Only Thursday is genuinely long, and Thai speakers cut it short too.

The mark that switches a letter off

Look at the ends of four of the day names: จันทร์, อาทิตย์, ศุกร์, เสาร์. Each finishes with a small circle-and-hook sitting on top of the last consonant. That is ทัณฑฆาต, usually called the karan, and its job is to tell you the letter underneath is not pronounced. It is a written instruction to ignore something, which is not a device English has.

It exists because these words are Sanskrit loans, and Thai kept the original spellings intact while the pronunciation shortened. ศุกร์ is shukra with its r switched off. จันทร์ is chandra with both the ท and the ร silenced by the one mark. The etymology is preserved on the page and the mouth is let off.

The practical consequence is that a karan changes where the syllable ends, and therefore the tone. In ศุกร์, if you read the ก as a final and the ร as silent, the syllable is dead, ศ is high class, and high class plus dead gives low tone: sùk. Ignore the mark and you would produce a second syllable that does not exist. Small mark, whole word.

The four short ones

วันจันทร์ — จ is a j and mid class, ั is a short a, น is a live n ending, and the ทร์ after it is switched off entirely. Mid class, live, no mark: mid tone. wan jan, Monday, and the same จันทร์ is the word for the moon.

วันพุธ — พ is a ph and low class, ุ is a short u written underneath, and ธ ends the syllable. A ธ at the end is not a th but a plain unreleased t, because a Thai final consonant only ever makes one of eight sounds no matter which letter is written. That is a stop, so the syllable is dead; a low class initial on a dead syllable with a short vowel gives high tone. wan phút, Wednesday.

วันศุกร์ — ศ is one of Thai's three s letters and it is high class, ุ is the same short u, ก is a dead k ending, ร์ is silent. High class, dead: low tone. wan sùk, Friday. The three ways of writing s all sound identical and differ only in class and in which loanwords they belong to, which is what the classes are actually doing.

วันเสาร์ — the เ at the front and the า after the consonant are one vowel wrapped around ส, giving an ao sound. It ends in a glide rather than a stop, so the syllable is live; ส is high class; high class, live, no mark gives rising. wan sǎo, Saturday. The ร์ is switched off again.

The three long ones

วันอาทิตย์ — two syllables. อา is อ, the silent carrier that has to stand in front of a syllable beginning with a vowel, plus a long า: aa, mid tone. Then ทิตย์: ท is a low-class th, ิ is a short i, ต closes it as a t, and the ย underneath the karan is silent. Low class, dead, short vowel: high tone. wan aa-thít, Sunday. อาทิตย์ on its own also means a week, so อาทิตย์หน้า is next week.

วันอังคาร — อัง is the silent อ again with a short a and a live ng, mid tone. คาร is a low-class kh, a long า, and a final ร that is pronounced n, not r, because r is not one of the eight sounds a Thai syllable can end on. Live, low class, no mark: mid tone. wan ang-khaan, Tuesday.

วันพฤหัสบดี — the hard one, and worth being honest about. Written in full it is phá-rúe-hàt-sà-baw-dii, five syllables, and it contains ฤ, a letter that behaves like neither a plain consonant nor a plain vowel and that you will meet perhaps a dozen times in total. In practice almost nobody says the whole thing. Thai speakers shorten it to พฤหัส, phá-rúe-hàt, or to วันพฤหัส, and the full form survives on formal documents and in the name of the planet. Read the short version and move on.

The colours, and where you actually see them

The colour attached to each day comes from court astrology, where every day has a presiding deity and a hue. The colour of the day you were born on is your สีประจำวันเกิด, your birthday colour, and it is not a museum piece. People wear it for luck, hospitals and offices hold colour days, and the association is common enough that asking a Thai person which day they were born on is a normal question rather than an odd one.

The most visible case is yellow. King Bhumibol was born on a Monday, and Monday is yellow, which is why yellow shirts appear in numbers around royal occasions and birthdays; his successor was also born on a Monday, so the colour has stayed. Light blue belongs to Friday and to Queen Sirikit, whose birthday on 12 August is also Mother's Day. Once you know the rule, a street full of one colour stops being decoration and starts being a date.

Temples encode it too. Many have a set of Buddha images for the days of the week, where you make an offering at the one matching your birth day. There are eight of them rather than seven, because Wednesday is split into a daytime and a night-time image, which is also why you will occasionally see Wednesday given two colours.

On a timetable, they get shorter

In real use the วัน usually falls away and the planet does the work alone. Opening hours run จันทร์–ศุกร์, Monday to Friday. A clinic notice will say ปิดวันอาทิตย์, closed Sunday, using the same ปิด that is printed on every shuttered shop door.

Calendars go further and cut each day to its first letter with a full stop after it: อา. จ. อ. พ. พฤ. ศ. ส. Two of those need a second letter to stay distinguishable, and the pattern tells you why. อ. alone would be ambiguous between อังคาร and อาทิตย์, so Sunday takes อา.; พ. would be ambiguous between พุธ and พฤหัสบดี, so Thursday takes พฤ. Reading a Thai calendar column is a two-letter problem, not a seven-word one.

One more word worth having: วันเกิด wan gòet, birthday. The เ–ิ– wrapped around ก is the same split vowel as in เปิด, open, and the ด ending makes it dead, so a mid-class ก gives low tone. It turns up in the same kind of short real strings as the door signs.

Where this sits in the order

Later than it looks. Phrasebooks put the days near the front because they are useful, but four of the seven end in a silenced letter and two of them are multi-syllable Sanskrit loans, which makes them poor first reading. Come to them once the consonant classes and the wrapped vowels are steady, and they take an evening. Come to them before that and you will be memorising shapes rather than reading them.

Phayan is an app for learning to read Thai script, and its 24 levels work letter by letter from zero through the 42 letters in current use, which is the order this post assumes. Every letter and word carries audio. Its typing engine has you assemble each word from letter variants and checks every pick, so a word like ศุกร์ has to be built with the right s rather than merely recognised. Items you get right come back at 1, 3, 7 and 21 days, three correct in a row retires one, and a single wrong answer sends it back to the start. Progress is kept on your device without an account, and the first five levels are free.

For the pieces underneath this one: the 32 vowel forms cover the wrapped เ–า and เ–ิ– shapes, the five tones with audio turn the tone at the end of each decode into a sound, and the Thai numerals are what sits next to the day names on an opening-hours notice. If none of that is in place yet, start with the script itself.

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