Days of the Week in Japanese and the Kanji Behind Them

Every day of the week in Japanese ends the same way, with 曜日 (ようび, youbi). Only the first kanji changes, and all seven of those are among the first characters anyone learns: moon, fire, water, tree, gold, earth and sun.

In conversation the final 日 often gets dropped. 月曜 (げつよう), 火曜 (かよう) and the rest mean exactly the same thing as the full forms.

Sun, moon and five planets

The seven names are the sun, the moon and the five planets you can see without a telescope. In Japanese, each of those planets is named after one of the five elements of classical Chinese thought, with 星 (せい, star) added:

If you know a Romance language, the mapping will look familiar. Tuesday is Mars's day (mardi in French, martes in Spanish), and 火曜日 is the Mars day. Wednesday belongs to Mercury (mercredi), and so does 水曜日. Thursday and Jupiter, Friday and Venus, Saturday and Saturn all line up the same way. English hides it because most of its day names switched to Norse gods, though Sunday, Monday and Saturday still show through.

The match comes from a shared source. The seven-day planetary week spread east across Asia and had reached Japan by way of China by around the 9th century. For the next thousand years it lived in astrological calendars and had little to do with daily life. It only became the working week after Japan adopted the Western calendar in 1873.

As for 曜, you'll almost never see it outside these seven words. It refers to a shining body in the sky, and the old term 七曜 (しちよう) means the seven luminaries.

The readings aren't the ones you learn first

Each of the seven kanji is also an ordinary word with a native Japanese reading: 月 is つき (moon), 火 is ひ (fire), 水 is みず (water), 木 is き (tree), 金 is かね (money), 土 is つち (soil) and 日 is ひ (sun, day). In the day names they take their Chinese-derived readings instead. On'yomi vs kun'yomi explains why most kanji have both kinds.

A few details catch learners out:

• 月 is げつ in 月曜日 but がつ in month names such as 一月 (いちがつ, January).
• 日曜日 uses 日 twice with two different readings, にち at the start and び at the end.
• 火曜日 and 土曜日 start with a single short sound, か and ど. Don't stretch them into かあ or どう.
• 金曜日 is きんようび, four sounds before the び: き, ん, よ, う. Running the ん into the よ gives you something closer to きにょうび.

One kanji on calendars, signs and timetables

Written Japanese shortens each day to its first kanji whenever space is tight. A date is usually followed by the day in brackets, so 10月16日(金) is Friday, October 16. You'll see the same shorthand on shop doors, timetables and TV listings:

• 月〜金 Monday to Friday.
• 土日 (どにち) Saturday and Sunday. This is also the everyday word for the two weekend days.
• 土日祝 (どにちしゅく) Saturdays, Sundays and public holidays. Common on train timetables and parking signs.
• 定休日 水曜 (ていきゅうび すいよう) Closed on Wednesdays. 定休日 is a shop's regular closing day.
• 月・水・金 Monday, Wednesday and Friday, as on a class schedule or a garbage collection notice.

Printed calendars in Japan most often start the week on Sunday, with Sundays and public holidays in red and Saturdays often in blue. Planners that start on Monday are easy to find too.

Mondays come up a lot on the holiday calendar. Several national holidays are fixed to a Monday, including Coming of Age Day (the second Monday of January) and Sports Day (the second Monday of October), and when a holiday lands on a Sunday the following Monday becomes a day off, marked 振替休日 (ふりかえきゅうじつ).

Asking what day it is

The question word is 何曜日 (なんようび, nan'youbi).

• 今日は何曜日ですか。 きょうはなんようびですか。 (Kyou wa nan'youbi desu ka.) What day is it today?
• 木曜日です。 もくようびです。 (Mokuyoubi desu.) It's Thursday.
• 休みは何曜日ですか。 やすみはなんようびですか。 (Yasumi wa nan'youbi desu ka.) Which day are you off?

Don't confuse it with 何日 (なんにち), which asks for the date, or 何月 (なんがつ), which asks for the month.

To say something happens on a day, add に: 土曜日に友達と会います (どようびにともだちとあいます, doyoubi ni tomodachi to aimasu) is "I'm meeting a friend on Saturday". In casual speech the に is often left out. For a span of days, use から and まで: 月曜日から金曜日まで働きます (げつようびからきんようびまではたらきます) is "I work from Monday to Friday". Our guide to Japanese particles covers に, から and まで in more detail.

The same word is how you settle on a day to meet. 何曜日がいいですか (なんようびがいいですか, Nan'youbi ga ii desu ka) is "Which day suits you?", and a natural reply is to suggest one: 水曜日はどうですか (すいようびはどうですか, Suiyoubi wa dou desu ka), "How about Wednesday?" To say you're free or busy, 土曜日は休みです (どようびはやすみです) is "I'm off on Saturday" and 金曜日はちょっと (きんようびはちょっと) is the usual soft way to say Friday doesn't work.

This week, next week, every week

今週, 来週, 先週 and 毎週 don't take に. Join them to a day with の, or with nothing at all after 毎週: 来週の火曜日 (らいしゅうのかようび) is next Tuesday, 先週の日曜日 (せんしゅうのにちようび) is last Sunday, and 毎週金曜日 (まいしゅうきんようび) is every Friday.

Watch out for 平日. It means Monday to Friday, so on a train timetable Saturday is not a 平日 even if you happen to be working that day.

To fix the order in your head, do what Japanese speakers do and recite only the first kanji: 月火水木金土日 (げつ、か、すい、もく、きん、ど、にち). Say it a handful of times and it stays put.

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