Days of the Month: 〜日

Meaning & Usage

In Japanese, the day of the month is expressed using the suffix 日にち, attached to a number. Unlike English, which tacks "-st," "-nd," "-rd," or "-th" onto any number, Japanese uses a system of irregular readings that follow no single rule. It comes up in the first week of most N5 courses and appears reliably on the actual exam.

There are two main phonetic patterns used for 日にち・か as a date counter:

• 〜か (ka): Used for the 2nd through 10th, as well as the 14th, 20th, and 24th. These readings come from native Japanese (和語わご) counting words that predate the introduction of Chinese-derived numbers.
• 〜にち (nichi): Used for the 11th through 31st, with the exceptions noted above. These come from Sino-Japanese (漢語かんご) number words that entered the language from Chinese.

The most important irregular reading is 一日ついたち (the 1st). The word ついたち derives from the classical expression 月つき立たち (tsukitachi), meaning "the rising of the moon" — referring to the new moon that marked the start of a lunar month in ancient Japan. Japan adopted the Gregorian calendar in 1873, but this old word stayed in everyday speech.

Similarly, 二十日はつか (the 20th) has a completely irregular reading — はつか — that cannot be derived from any regular number pattern. Both 十四日じゅうよっか (the 14th) and 二十四日にじゅうよっか (the 24th) also use the 〜か pattern: the digit 4 borrows the native Japanese reading よ, forming よっか rather than the Sino-Japanese し or よん.

Dates come up in every corner of Japanese life — business emails, hospital check-ins, school calendars, train timetables, receipts. Getting these forms right early makes a real difference. The irregular readings are unusual even by Japanese standards; regular exposure is what makes them automatic.

Structure & Formation

The basic rule is to attach 日にち or 日か after the number word. However, the reading of both the number and 日にち changes depending on the specific date. The table below is a complete reference for all days of the month:

To ask "what day of the month is it?", use 何日なんにちですか (nan-nichi desu ka). This question form is essential for everyday scheduling conversations and appears frequently in both real life and JLPT listening exercises.

Example Sentences

Basic Date Statements

Birthdays and Anniversaries

Schedules and Appointments

Past Events

Future Plans

Common Mistakes

Mistake 1: Reading 一日 as いちにち instead of ついたち

❌ 今日きょうは一日いちにちです。

✅ 今日きょうは一日ついたちです。

The most common beginner error is applying the standard Sino-Japanese number reading (いち) to 一日ついたち. When referring to the 1st day of the month, ついたち must always be used. Note that いちにち does exist in Japanese — but it means "one full day" as a duration (24 hours), not a calendar date. Confusing these two creates a fundamental communication error.

Mistake 2: Reading 二十日 as にじゅうにち

❌ 試験しけんは二十日にじゅうにちです。

✅ 試験しけんは二十日はつかです。

The 20th carries a completely irregular reading — はつか — that cannot be predicted from the regular pattern. Many learners expect にじゅうにち by analogy with 二十一日にじゅういちにち, but 二十日はつか is its own special form. Treat it as a standalone vocabulary item that must be memorized independently.

Mistake 3: Forgetting that 14 and 24 use 〜か

❌ 会議かいぎは十四日じゅうしにちです。

✅ 会議かいぎは十四日じゅうよっかです。

After mastering days 1–10, learners sometimes assume that all two-digit dates from 11 onward use 〜にち. This leads to errors on 十四日じゅうよっか (14th) and 二十四日にじゅうよっか (24th), which both use 〜か because the digit 4 borrows the native Japanese reading よ, forming よっか. Memorize these two exceptions alongside the 〜か group for days 1–10.

Mistake 4: Confusing 日 as a date versus a duration

❌ 旅行りょこうは三日みっかでした。(Intended meaning: "The trip was three days long")

✅ 旅行りょこうは三日間みっかかんでした。

三日みっか most naturally refers to "the 3rd (of the month)." To express a duration of three days, add the suffix 〜間かん: 三日間みっかかん. Similarly, 五日いつか means "the 5th," while 五日間いつかかん means "for five days." The distinction matters whenever context alone cannot resolve the ambiguity.

Mistake 5: Using the wrong particle with dates

❌ 試験しけんは十日とおかで行いきます。

✅ 試験しけんは十日とおかに行いきます。

When indicating a specific point in time — including dates — always use the particle に. The particle で marks means, method, or location of an action, not time. This applies to all time expressions: 月曜日げつようびに (on Monday), 三時さんじに (at 3 o'clock), 一月いちがつに (in January). Mixing up に and で is one of the most common N5-level particle errors.

Cultural Notes

Japan runs on precise scheduling. Dates appear everywhere — on official documents, business emails, train timetables, and school notices. Being fluent with them immediately marks you as someone who actually uses the language rather than just studies it.

The expression 一日ついたち (the 1st) has ancient roots in the traditional Japanese lunar calendar. The first day of each lunar month coincided with the new moon, and the word ついたち comes from 月つき立たち — the moon "standing up" or appearing anew. Even after the Meiji government switched to the Gregorian calendar in 1873, ついたち stayed in everyday speech — a small trace of the old lunar world.

四月しがつ一日ついたち (April 1st) is especially significant in Japan. Unlike many countries where the academic year begins in September, Japanese students start school on April 1st. Most companies and government offices also begin their fiscal year on this date. This makes April 1st one of the most culturally loaded dates in the Japanese calendar — a day of beginnings, ceremonies, and fresh starts.

In formal writing, Japanese dates follow the order 年ねん・月がつ・日にち (year-month-day), which aligns with the ISO 8601 international standard but differs from the American month-day-year format. Japan also maintains the 元号げんごう (era name) system in official documents: the current era is 令和れいわ, which began in May 2019. In formal contexts, you may see dates written as 令和れいわ8年ねん3月がつ21日にち (Reiwa 8, March 21) alongside or instead of the Western year.

Related Grammar Points

• もう — Already, Not Anymore, One More (Grammar N5)
• に (ni) — Direction, Time, and Location Particle (Grammar N5)
• 〜人: Counting People in Japanese (Grammar N5)
• まだ — Still, Not Yet (Grammar N5)
• 〜本: Counter for Long, Cylindrical Objects (Grammar N5)
• まで — Until, To (Extent Particle) (Grammar N5)

JLPT Tips

On JLPT N5, 〜日にち・か appears in vocabulary questions, reading passages about schedules, and listening dialogues involving appointments. Irregular readings are a deliberate focus — they can't be guessed from the numbers alone, which makes them a reliable test of whether someone has genuinely studied the system.

The highest-priority irregular readings to memorize for N5 are: 一日ついたち、二日ふつか、三日みっか、四日よっか、八日ようか、十日とおか、二十日はつか. These appear most often in exam questions and are the forms most likely to be used as distractors against each other.

One method that works well: memorize the first ten days as a rhythmic chant — ついたち、ふつか、みっか、よっか、いつか、むいか、なのか、ようか、ここのか、とおか. Say it out loud each day until it flows without effort. Then add the three exceptions: 十四日じゅうよっか、二十日はつか、二十四日にじゅうよっか.

In the listening section, dates come up fast — embedded in conversations about school events, travel plans, or doctor visits. The 〜か readings sound nothing like the numbers they're built from, so learners who only study reading are often caught off guard. Regular exposure to real Japanese audio — dramas, news clips, podcasts — builds the ear faster than any drill sheet.

For reading comprehension questions about schedules or calendars, always check both the 月がつ (month) and 日にち (day) together. Exam distractors often change just one element. A classic N5 trap is confusing 六日むいか (the 6th) with 六月ろくがつ (June), or 七日なのか (the 7th) with 七月しちがつ (July). Read carefully and never assume.