Reference sheet

The calendar

The seven days and the planets they are named after, all twelve months in Japanese and in both Arabic systems, every date from the 1st to the 31st, and the twelve old Japanese month names — in Japanese, English and Modern Standard Arabic. Made to print.

Taught in lesson 10 · readings from Jisho.org (JMdict) · calendar history from the National Astronomical Observatory of Japan and the National Diet Library

1.The shape of it, in two lines

Japanese names its days and numbers its months. A weekday is one element character plus 曜日; a month is a number plus 月.
Arabic does the reverse. Five days are simply counted, two are named for worship and rest; the months are borrowed names.

2.The seven days

Tap any word to hear it. The middle column is the classical planetary order, which is also the order of the Japanese week. Five day names open with exactly the reading of their planet — 火星 kasei gives 火曜日 kayōbi — and the two that do not are the Sun and the Moon, which are not planets.

This chart is rendered from assets/week-data.js and needs JavaScript.

The names reached Japan in 806, carried back from Tang China by Kūkai in the 宿曜経 along with over 460 other volumes, and were used for a thousand years to judge whether a day was lucky. Japan did not rest on a seven-day cycle until Cabinet Order No. 27 of 12 March 1876 made Sunday a holiday; before that, offices closed on days containing a 1 or a 6.

3.The twelve months

Number plus 月 gatsu. Three keep the classical readings of their number and are marked below. Both Arabic columns are Modern Standard: the first is used in Egypt, Sudan, Yemen and the Gulf, the second in Iraq and the Levant, and pan-Arab media often print both.

#	Japanese	Arabic — Egypt & Gulf	Arabic — Iraq & Levant
1	一月いちがつ ichigatsu	يَنايِر	كانُون الثانِي
2	二月にがつ nigatsu	فِبْرايِر	شُباط
3	三月さんがつ sangatsu	مارِس	آذار
4	四月しがつ shigatsunot よんがつ	أَبْرِيل	نَيْسان
5	五月ごがつ gogatsu	مايُو	أَيّار
6	六月ろくがつ rokugatsu	يُونِيُو	حَزِيران
7	七月しちがつ shichigatsuなながつ is heard	يُولِيُو	تَمُّوز
8	八月はちがつ hachigatsu	أَغُسْطُس	آب
9	九月くがつ kugatsunever きゅうがつ	سِبْتَمْبَر	أَيْلُول
10	十月じゅうがつ jūgatsu	أُكْتُوبَر	تِشْرِين الأَوَّل
11	十一月じゅういちがつ jūichigatsu	نُوفَمْبَر	تِشْرِين الثانِي
12	十二月じゅうにがつ jūnigatsu	دِيسَمْبَر	كانُون الأَوَّل

The Levantine names are Babylonian by descent and cousin to the Hebrew month names — نَيْسان is Nisan, تَمُّوز is Tammuz, أَيْلُول is Elul. Note the two pairs that count themselves: تِشْرِين الأَوَّل and تِشْرِين الثانِي are first and second Tishrin, كانُون الأَوَّل and كانُون الثانِي first and second Kanun — so December and January are the same month named twice, which is why the year break falls inside a pair. In the Gulf and Jordan you will also simply hear الشَّهْر السَّابِع, “the seventh month”, which is the Japanese system exactly.

4.Every date, 1 to 31

The first ten are the old native numbers plus か, an ancient word for day. From the 11th it is the ordinary number plus にち — except for the four marked below, which never regularised.

#	Kana	Romaji
1	ついたち	tsuitachi	From 月立ち, “the moon rising”
2	ふつか	futsuka
3	みっか	mikka
4	よっか	yokka
5	いつか	itsuka
6	むいか	muika
7	なのか	nanoka
8	ようか	yōka	Three beats, like よっか — the middle one differs
9	ここのか	kokonoka
10	とおか	tōka
11	じゅういちにち	jūichinichi	The regular pattern starts here
12	じゅうににち	jūninichi
13	じゅうさんにち	jūsannichi
14	じゅうよっか	jūyokka	Keeps よっか. Never じゅうよんにち
15	じゅうごにち	jūgonichi
16	じゅうろくにち	jūrokunichi
17	じゅうしちにち	jūshichinichi	じゅうななにち also standard
18	じゅうはちにち	jūhachinichi
19	じゅうくにち	jūkunichi	Keeps く. Not じゅうきゅうにち
20	はつか	hatsuka	Wholly irregular. From はた, an old twenty
21	にじゅういちにち	nijūichinichi
22	にじゅうににち	nijūninichi
23	にじゅうさんにち	nijūsannichi
24	にじゅうよっか	nijūyokka	Keeps よっか again
25	にじゅうごにち	nijūgonichi
26	にじゅうろくにち	nijūrokunichi
27	にじゅうしちにち	nijūshichinichi	にじゅうななにち also standard
28	にじゅうはちにち	nijūhachinichi
29	にじゅうくにち	nijūkunichi	にじゅうきゅうにち also standard
30	さんじゅうにち	sanjūnichi	Also みそか, the month's last day
31	さんじゅういちにち	sanjūichinichi

みそか survives mainly in おおみそか — the great last day, New Year's Eve. A full date runs largest to smallest, the reverse of English: 2026年8月5日 is にせんにじゅうろくねんはちがついつか.

5.A point in time, or a length of it

The same characters read two ways. This is lesson 6's かん distinction — なんじ against なんじかん — reappearing in the calendar.

Written	A point	A length
一月	いちがつ January	ひとつき one month
一日	ついたち the 1st	いちにち one day
四月 / 四か月	しがつ April	よんかげつ four months long
一週 / 一週間	いっしゅう week one	いっしゅうかん a week long

The rule: the old readings (ししちく) name; the modern ones (よんななきゅう) count.

6.This one, last one, next one

	Week	Month	Year	Arabic pattern
this	こんしゅう	こんげつ	ことし	هٰذَا
last	せんしゅう	せんげつ	きょねん	الْمَاضِي
next	らいしゅう	らいげつ	らいねん	الْقَادِم

The year breaks the pattern twice — ことし not こんねん, きょねん not せんねん. Arabic makes no such exception: the three modifiers attach unchanged to الْأُسْبُوع, الشَّهْر and السَّنَة.

7.The twelve old month names

Before 1873 Japan ran a lunisolar calendar whose months had names rather than numbers — the 和風月名. They are no longer how anyone tells you a date, but they are everywhere in poetry, brand names and personal names, and two are still ordinary words: やよい and しわす.

#	Name	Reading	What it is said to mean
1	睦月	mutsuki	The month of harmony — families gathering at New Year
2	如月	kisaragi	Also written 衣更着 — “wearing more clothes”, the cold returning
3	弥生	yayoi	Growing thick — plants coming up
4	卯月	uzuki	The month of the u flower, deutzia
5	皐月	satsuki	The month of planting rice seedlings
6	水無月	minazuki	The 無 is “of”, not “none” — the month of water, when the paddies are flooded
7	文月	fumizuki	From 穂含月 — the month the rice ears fill
8	葉月	hazuki	The month leaves fall — which only makes sense on the old calendar
9	長月	nagatsuki	From 夜長月 — the month of long nights
10	神無月	kannazuki	“The month of the gods” — popularly, the month they are all away at Izumo
11	霜月	shimotsuki	The month of frost
12	師走	shiwasu	Even the masters run — the month nobody has time

Etymologies from the National Diet Library's 和風月名, which is explicit that they are 諸説あり — several accounts exist and none is settled. Two things are worth knowing about them. They sit one to two months later than the modern month of the same number, which is why the eighth month is about falling leaves; and the old almanacs did not actually print them — Edo-period calendars wrote 正月・二月・三月, plain numbers, exactly as Japanese does today.

8.Fifty-three words

Everything on this sheet as cards, grouped by meaning; tap any word to hear it.

These cards are rendered from assets/vocab10-data.js and need JavaScript.

Readings, glosses and commonness tags from Jisho.org, serving JMdict/EDICT. Calendar history from the National Astronomical Observatory of Japan's 暦Wiki and the National Diet Library's 日本の暦; the transmission of the seven-day week from ja.wikipedia, 曜日. Arabic day forms from en.wiktionary, month systems from en.wikipedia, both checked against Madinah Arabic and Almaany. For the question words that ask about any of this, see the question-word sheet.