Esperanto vs Ido: differences, history and speakers

Ido is a constructed language presented in Paris in 1907 as a "reformed Esperanto". It keeps Esperanto's roots and fixed endings but drops the accented letters, forms the plural with -i, does not make adjectives agree with nouns and uses the accusative -n only in unusual word order. Its name is the Esperanto word ido, "offspring".

A committee of the Delegation for the Adoption of an International Auxiliary Language, driven by the philosopher and logician Louis Couturat, accepted Esperanto only "with reforms" in October 1907. Most Esperanto speakers did not follow. Even the lowest central estimate for Esperanto (about 60,000 speakers) is more than ten times the highest figure quoted for Ido (5,000).

For Volapük, Interlingua and other rivals, see Esperanto compared with other constructed languages.

#Speakers: Esperanto and Ido in numbers

No census counts the speakers of either language worldwide, so all speaker figures are estimates, and the last row compares different years. "Active editors" made an edit in the previous 30 days.

#History: the 1907 committee and the split

The Delegation was founded in January 1901 by Léopold Leau and Couturat to have scholars choose one international language. By 1907 it had the backing of 310 societies and about 1,250 academics. In May 1907 the International Association of Academies in Vienna declared itself not competent, so the Delegation appointed its own committee.

The committee met in Paris from 15 to 24 October 1907. Louis de Beaufront, a leading French Esperantist, presented Esperanto, because the rules barred its author, Zamenhof, from doing so. Near the end an anonymous project signed "Ido" appeared, and the committee accepted Esperanto in principle, with changes to be settled by a permanent commission.

Beaufront admitted in 1908 that he was "Ido". The Enciklopedio de Esperanto (1934) says Beaufront "turned out to be its chief author, or was proclaimed as such"; later authors, such as Detlev Blanke, see it mainly as Couturat's work, with Beaufront as its public face. Sources differ on how the work was shared.

Zamenhof had proposed similar reforms in 1894, and his readers had voted them down; in 1907 he warned that the committee had no authority. English Wikipedia says the commission gave the Esperanto Language Committee one month to accept the reforms and broke off relations when no answer came. The 1905 Fundamento had made the language's core binding (see history).

The Enciklopedio says about 20% of Esperanto's leaders but only 3–4% of ordinary Esperantists switched. Esperantists dispute the committee's legitimacy: of its 12 members, they say, only four took part. Ido's grammar answers that the vote to adopt Esperanto with changes was unanimous and blames the split on those who forgot their promises.

#Ido after 1907

Ido supporters formed an Academy and launched the monthly Progreso in 1908. The Delegation dissolved on 31 July 1910 after founding the Union for the International Language Ido (ULI), still its official body.

Couturat died on 3 August 1914 in a car collision, at the start of the First World War. In 1928 Otto Jespersen left for his own language, Novial. Ido has changed little since 1922.

#Main differences in grammar and vocabulary

See the accusative and nouns and adjectives for the Esperanto side. In Ido, frato alone means "sibling".

The languages are close: German Wikipedia, following Detlev Blanke, puts the difference in grammar and vocabulary at no more than 15%. False friends exist: grava means "important" in Esperanto but "heavy" in Ido, and legi means "to read" but "laws". Vikipedio traces the suffix -end-, official in Esperanto since 1953, to Ido.

#The Lord's Prayer in both languages

The opening of the Lord's Prayer: Zamenhof's wording from the first Esperanto textbook (1887) and Beaufront's Ido translation printed in 1924. Zamenhof died in 1917, Beaufront in 1935.

Esperanto:

Patro nia, kiu estas en la ĉielo, sankta estu Via nomo, venu reĝeco Via, estu volo Via, kiel en la ĉielo, tiel ankaŭ sur la tero.

Ido:

Patro nia qua esas en la cieli, Vua nomo santigesez; Vua regno arivez; Vua volo esez obediata, quale en la cielo, anke (tale) sur la tero.

English: Our Father, who is in heaven, hallowed be Your name; Your kingdom come; Your will be done, as in heaven, so also on earth.

Compare kiu estas and qua esas "who is", kiel and quale "as", ankaŭ and anke "also". The Esperanto command is estu; the Ido command is esez. More in our sample texts.

#Which should you learn: Esperanto or Ido?

Learn Esperanto if you want people to talk to, and consider Ido if its rules appeal to you.

Ido suits a learner who dislikes accented letters and case endings, or who knows Romance languages well. It has translations of The Little Prince, the Psalms and the Gospel of Luke, and magazines such as Progreso, but its community is small, so partners, courses and books are few.

Esperanto has the same basic grammar plus native speakers, annual congresses, a large Wikipedia, a free course and a long literature. Its accents and accusative are the usual objections (criticism of Esperanto). The languages are close, so learning one gives a start on reading the other.

#Common questions

#What is the difference between Esperanto and Ido?

Ido is Esperanto reformed in 1907. It has no accented letters, plural -i, invariable adjectives, an accusative used only when needed, gender-neutral roots and more Romance vocabulary.

#Is Ido easier than Esperanto?

Ido removes some endings and the accented letters, which many learners like. It adds extra suffixes, less regular question words and digraph spelling. We found no published experiment comparing learning times, so "easier" depends on your languages and goals.

#How many people speak Ido?

Published estimates run from 100–200 (2000) to 1,000–5,000 (Ido Foundation). Nobody has counted; Finland's register lists 25 people with Ido as mother tongue. Esperanto estimates start at about 60,000.

#Why did Ido split from Esperanto?

Couturat and Beaufront wanted to remove what they saw as Esperanto's flaws, and a Delegation committee backed their project in October 1907. Most Esperantists refused to change a language already fixed by the 1905 Fundamento.

#Is Ido still used?

On a small scale. The ULI holds yearly conventions, Progreso appears, and the Ido Wikipedia has 64,732 articles. Daily use is far smaller than Esperanto's.

#Sources

• Wikipedia, Ido, Comparison between Esperanto and Ido, Delegation for the Adoption of an International Auxiliary Language, Louis de Beaufront, 1894 Esperanto reform project, Union for the International Language Ido
• Wikipedia (fr), Délégation pour l'adoption d'une langue auxiliaire internationale; Wikipedia (de), Ido (Sprache)
• Vikipedio, Esperanto kaj Ido komparataj (quoting the Enciklopedio de Esperanto), Louis Couturat, Patro nia (Zamenhof's 1887 text, Unua Libro p. 19)
• Enciklopedio de Esperanto (Budapest, 1934), articles "Ido" and "Reformoj en E", copies: part 1 and part 3; Otto Jespersen, History of our language (Ido) (1912, English translation); Henry Jacob, A Planned Auxiliary Language, chapter on Ido (1947); Léopold Leau, The Truth about the Delegation in 1907, Progreso, August 1933; Detlev Blanke, Internationale Plansprachen (Berlin, 1985), p. 187, and Ivo Lapenna, Ulrich Lins, Tazio Carlevaro, Esperanto en perspektivo (Rotterdam, 1974), p. 423, both as cited in German Wikipedia: Ido (Sprache) and Wilhelm Ostwald
• MacTutor, Louis Couturat; Encyclopedia.com, Couturat, Louis
• Wikipedio, Ido (Beaufront's Patro nia, from Bulletin Français-Ido, Nov–Dec 1924, p. 288), Historio di Ido
• Beaufront, Kompleta Gramatiko Detaloza di la Linguo Internaciona Ido (1925), Quo esas Ido? and Substantivo on Wikisource
• PMEG, O-vortoj, A-vortoj, -in-, -end-; Wiktionary, grava, lego
• Ido Foundation, IDO; Detlev Blanke (2000), cited in Sabine Fiedler, Phraseology in planned languages, De Gruyter, 2007, p. 779
• Statistics Finland, Population by language, table 11rm, and Wikimedia statistics for Esperanto and Ido Wikipedia (all retrieved 8 October 2026)