Locale Eo 001

Reference data for the Esperanto locale — endonym Esperanto, written in the Latin script, left-to-right (LTR).

Identifiers

• BCP 47 tag: eo-001
• ISO 639-1: eo
• ISO 639-3: epo
• Script: Latn (Latin)
• Region: 001 (World)
• Text direction: ltr — left-to-right (LTR)

Speakers (approximate)

• L1 (native): 2,000
• L2 (additional): 2,000,000
• L1+L2 (total): 2,002,000

Pluralization

CLDR plural categories for this locale: one, other (2 forms).

• one — n = 1 (e.g. 1)
• other — everything else (e.g. 0, 2~16, 100, 1000, …)

See Unicode Messageformat for writing plural messages using these categories.

Translating into this locale

Esperanto is a planned language with a fixed grammar of sixteen rules (the Fundamento de Esperanto, 1905) and a worldwide community of speakers, most of whom learned it as a second language. Translate into clear, regular Esperanto rather than copying idiom from the source.

Translate ideas, not words.

• Esperanto has no national idioms; avoid translating English or other idioms literally, because readers come from many languages. Prefer clear, literal statements, or explain the idiom.
• Use the language's word-building system: prefixes and suffixes (mal-, re-, -ej-, -ist-, -ig-) and compounding, rather than borrowing foreign words unnecessarily.
• Watch for calques of English phrasal verbs and word order. Esperanto word order is free, but subject-verb-object is the neutral order and the accusative marks the object.

Grammar.

• Parts of speech are marked by endings: -o noun, -a adjective, -e adverb, -i infinitive, -as present, -is past, -os future, -us conditional, -u imperative or subjunctive.
• Plural is -j; the accusative is -n; adjectives agree with their nouns in number and case.
• Use the accusative for direction after a preposition ("Mi iras en la domon" is movement into the house), and a preposition "je" only when no other preposition fits.
• Correlatives form a table (kio, tio, io, nenio; kiu, tiu; kie, tie).

Register.

• There is one second-person pronoun, "vi", used for both singular and plural, formal and informal. "Ci" exists in the Fundamento but is rare. Politeness is carried by phrases like "bonvolu" and "mi petas".
• Writing is usually plain and international; avoid dialect and slang.

Orthography and typography.

• The alphabet has 28 letters, including six with diacritics: ĉ, ĝ, ĥ, ĵ, ŝ, ŭ. Use proper Unicode; the "x-system" (cx, gx) is a fallback only when characters cannot be displayed.
• Capitalization follows the usual European rules; months and days are lowercase.
• Numbers: decimal comma, space or period for thousands; dates "la 17-a de oktobro 2026".
• Quotation marks vary (« », „ “, " "); follow the project's convention.

Common pitfalls

• Dropping the accusative or the plural/adjective agreement.
• Using idioms or loan constructions that Esperanto speakers from other languages will not understand.
• Using the x-system when Unicode is available.
• Using "ci" for informal address in contemporary text.
• Inventing roots without checking the Plena Ilustrita Vortaro (PIV) or Akademio de Esperanto's Oficialaj Aldonoj.

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.
• Plena Ilustrita Vortaro (PIV) and Plena Manlibro de Esperanta Gramatiko (PMEG, Bertilo Wennergren)
• Akademio de Esperanto (https://www.akademio-de-esperanto.org)