Two calendars
Japan uses both the Western calendar and an era-based one that counts years from the start of each emperor's reign. Both are current, and which one a document uses depends on the document.
Official and municipal paperwork frequently uses era years, sometimes with no Western option, which is why a resident needs to know at least their own key dates in that system.
- Municipal forms and official records usually use era years.
- Business documents commonly use the Western calendar.
- Some forms print both and let you choose.
- Contracts and legal documents vary; follow the form.
- Your birth year in the era calendar is worth memorising.
Writing a date
Japanese dates run from the largest unit to the smallest: year, then month, then day. That order is consistent across both calendars and across horizontal and vertical writing.
The characters for year, month and day are written after each number, which is the part that looks unfamiliar at first and quickly stops being so.
| Japanese | Romaji | Meaning |
|---|---|---|
| 二〇二六年九月十日 | nisen nijūroku-nen kugatsu tōka | 10 September 2026, kanji numerals |
| 2026年9月10日 | nisen nijūroku-nen kugatsu tōka | The same date, Arabic numerals |
| 令和八年九月十日 | Reiwa hachi-nen kugatsu tōka | The same date in the era calendar |
| 生年月日 | seinengappi | Date of birth, a form field |
| 記入日 | kinyūbi | Date of completion |
| 年月日 | nen gappi | Printed as a template on forms |
The two numeral systems
Japanese writes numbers with Arabic numerals or with kanji, and which is used depends on the direction of the text and the formality of the document.
Horizontal business writing overwhelmingly uses Arabic numerals. Vertical writing uses kanji numerals, and formal documents may use them in either direction.
| Context | Numerals | Note |
|---|---|---|
| Horizontal business text | Arabic | The default |
| Vertical text | Kanji | Follows the direction |
| Formal certificates | Kanji | Often the elaborate forms |
| Forms | Match the form | Whatever is printed |
| Prices and quantities | Arabic | Even in vertical menus |
| Addresses | Either | Follows the document |
The rule that never fails is the fourth row. Matching what the document already uses is always acceptable.
Grouping in ten thousands
Japanese groups large numbers in units of ten thousand rather than thousand, which means the comma grouping used in Western writing does not align with the words being said.
This is a genuine source of error under pressure, particularly in finance and in any figure above a million, and confirming large numbers back is standard practice for that reason.
| Japanese | Romaji | Meaning |
|---|---|---|
| 一万 | ichiman | Ten thousand |
| 十万 | jūman | One hundred thousand |
| 百万 | hyakuman | One million |
| 一千万 | issenman | Ten million |
| 一億 | ichioku | One hundred million |
| 三億五千万 | sanoku gosenman | Three hundred and fifty million |
The unit changes at every four digits rather than every three. Counting digits in fours is the reliable way to convert quickly.
Numbers in vertical text
Vertical writing appears on signs, book spines, formal letters and some forms, and numbers in it are written with kanji numerals running down the column.
The long vowel mark in katakana also rotates in vertical text, which is worth knowing because it looks like a different character at first.
- Kanji numerals are used, running down the column.
- The date order remains year, month, day.
- The katakana long vowel mark becomes a vertical stroke.
- Arabic numerals do appear, usually rotated or in short runs.
- Prices and quantities often stay in Arabic numerals regardless.
Filling in a form
The practical rule for forms is to match what is printed. If the form shows an era name, use the era year; if it shows a Western-style field, use that; if it prints the year, month and day characters, fill in only the numbers.
Where a form is ambiguous, asking is entirely routine and is faster than guessing and being asked to redo it.
| Japanese | Romaji | Meaning |
|---|---|---|
| 和暦でしょうか、西暦でしょうか。 | Wareki deshō ka, seireki deshō ka. | Era calendar or Western calendar? |
| こちらは何を書けばいいですか。 | Kochira wa nani o kakeba ii desu ka. | What should I write here? |
| 記入例はありますか。 | Kinyūrei wa arimasu ka. | Is there a filled-in example? |
| ここは空欄でよろしいですか。 | Koko wa kūran de yoroshii desu ka. | Is it all right to leave this blank? |
| 数字は算用数字でいいですか。 | Sūji wa san'yō sūji de ii desu ka. | Are Arabic numerals acceptable? |
| 書き直したほうがいいですか。 | Kakinaoshita hō ga ii desu ka. | Should I rewrite it? |