Locale Ja 001

Reference data for the Japanese locale — endonym 日本語, written in the Japanese script, left-to-right (LTR).

Identifiers

• BCP 47 tag: ja-001
• ISO 639-1: ja
• ISO 639-3: jpn
• Script: Jpan (Japanese)
• Region: 001 (World)
• Text direction: ltr — left-to-right (LTR)

Speakers (approximate)

• L1 (native): 123,000,000
• L2 (additional): 3,000,000
• L1+L2 (total): 126,000,000

Regional variants

This is the base/macro locale for Japanese. Region-specific variants in this dataset:

• Locale Ja Jp (Japanese (Japan))

Pluralization

CLDR plural categories for this locale: other (1 form).

• other — everything else (e.g. 0~15, 100, 1000, 10000, …)

See Unicode Messageformat for writing plural messages using these categories.

Translating into this locale

Japanese is written in a mix of kanji, hiragana, katakana, and Latin letters, with politeness built into verb forms. Translate for the reader's relationship to the speaker, not just the meaning. See Locale Ja Jp.

Translate ideas, not words.

• Japanese is subject-omitting and context-driven. English pronouns ("you", "we", "I") are usually dropped; do not translate "you" as あなた, which sounds distant or even rude. Address the user with a role (お客様, ユーザー) or leave the subject out.
• Sentence order is subject-object-verb with the verb last; modifiers precede the noun. Long English relative clauses should be split into sentences.
• Japanese prefers short, concrete verbs and noun-ending (体言止め) in UI and headings: "ファイルの保存".
• English passives and "can/will" statements become natural active forms: "You can save the file" is "ファイルを保存できます".
• Re-express idioms by meaning: "it's a piece of cake" is "朝飯前だ" or "簡単だ".
• Avoid excessive katakana loanwords when a common Japanese word exists, and avoid kanji compounds that are too formal for the audience.

Grammar that trips translators.

• Particles mark roles: は (topic), が (subject), を (object), に, で, へ, と. Mixing は and が changes the nuance.
• Counters: Japanese uses counters with numerals (1つ, 3人, 5枚, 2台).
• Verb forms encode politeness, tense, and mood; adjectives conjugate.
• Plurals are usually unmarked; use numerals or context.
• Tense: present/non-past and past; progressive with ている.

Register.

• Japanese has at least three politeness levels: plain form (だ・である), polite form (です・ます), and honorific/humble forms (keigo: 尊敬語, 謙譲語, 丁寧語). UI, manuals, and customer text normally use です・ます; official and technical documents may use だ・である; business emails use keigo.
• Do not mix です・ます and だ・である within one text. Use お客様 or 様 and avoid 〜さん in formal contexts.
• Japanese customer-facing text is more polite and apologetic than English: use cushion words (恐れ入りますが, 申し訳ございません) where tone requires.

Orthography and typography.

• Punctuation: 、 and 。 (full-width), quotation marks 「 」 and 『 』, and wave dash 〜. Use full-width brackets（ ） in Japanese sentences.
• Do not add spaces between Japanese words; there are no spaces between Japanese and Latin letters or digits in most Japanese style,.
• Numbers: Arabic digits in UI; kanji numerals in set phrases and vertical text. Dates: 2026年10月17日; 24-hour clock (17時30分).
• Katakana long vowel mark ー: Microsoft style keeps the final ー for words ending in -er, -or, -ar (ユーザー, サーバー), while JIS standards omit it (ユーザ). Follow the project's style consistently.
• Half-width katakana is not used; use full-width katakana and half-width alphanumerics.

Common pitfalls

• Translating "you" as あなた or keeping every pronoun.
• Mixing です・ます with だ・である, or inconsistent keigo.
• Overusing katakana loanwords or kanji compounds.
• Using Western punctuation (. ,) or Western quotes instead of 、。「」.
• Inconsistent use of the long vowel mark ー.
• Literal translations of English passives and "please" patterns.
• Breaking lines or applying line-breaking rules (kinsoku) incorrectly.

Learn more

• Locale for BCP 47 identifiers, locale-sensitive formatting, pluralization, and text-direction concepts that apply across all locales.
• Unicode Messageformat for writing plural/selection messages correctly for this locale's grammar.
• Microsoft Localization Style Guide, Japanese (https://aka.ms/japanese-styleguide)
• Agency for Cultural Affairs (Bunka-chō), 公用文作成の考え方 and 現代仮名遣い guidance