Esperanto numbers: 0–100, ordinals, dates and time

Esperanto counts with 13 basic words: nul (0), unu (1) to naŭ (9), dek (10), cent (100) and mil (1000). The rule from the Fundamento (rule 4) is simple: numbers written together multiply, numbers written apart add. So dudek = 2 × 10 = 20, and dek du = 10 + 2 = 12.

12: dek du = 10 + 2

12

dek10+du2

20: dudek = 2 × 10

20

dudek2 × 10

2026: du mil dudek ses = 2 × 1000 + 2 × 10 + 6

2026

du mil2 × 1000+dudek2 × 10+ses6

Number words never change: they take no plural -j and no accusative -n. Mi havas du fratojn – "I have two brothers". The one exception is unu in the sense "some": unuj … aliaj – "some … others" (PMEG).

To convert any number automatically, use the number converter.

#Numbers 0–10

Every letter is pronounced, and c always sounds like "ts" (see the alphabet). Ses (6) and sep (7) are easy to confuse, so say them clearly.

#Numbers 11–20

Numbers 11–19 are dek plus a unit, written as two words.

#Numbers 21–100: one rule

Tens are one word: unit + dek. Any number from 21 to 99 is the ten, a space, then the unit.

#Hundreds, thousands and millions

Hundreds also join into one word: ducent (200), tricent (300), naŭcent (900). Everything else is written separately. Thousands are always a separate word: du mil (2000), not dumil (PMEG). Do not use hyphens: cent tridek du, not cent-tridek-du.

Miliono and miliardo are nouns, so they take -j and da: dek milionoj da homoj – "ten million people". Esperanto uses the long scale: biliono is 10¹², not the English "billion" (10⁹), which is miliardo (PMEG).

#Ordinal numbers: -a

Add the adjective ending -a to get ordinals: unua "first", dua "second", tria "third", kvara, kvina, sesa, sepa, oka, naŭa, deka "tenth". Ordinals agree like any adjective: la unuaj tagoj, la sepan tagon.

In compound ordinals PMEG recommends a hyphen as clearer: dek-unua "eleventh", dudek-unua "twenty-first". Dudek unua also appears. In figures, write 1-a, 21-a.

With -e you get adverbs: unue "firstly", due "secondly". With -o you get nouns: unuo "a unit", dekduo "a dozen", cento "a hundred".

#Fractions, multiples and groups

Rule 4 of the Fundamento adds three suffixes for numbers and the preposition po.

-obl- and fojo differ: duobla pago is a double payment, dufoja pago is a payment made twice (PMEG).

Esperanto uses a decimal comma: 3,5 is read tri komo kvin. Arithmetic is plain: du plus du estas kvar (2 + 2 = 4), dek minus tri estas sep, sep dividite per du estas tri komo kvin (PMEG).

#Dates

A date is la + ordinal + de + month (+ year). The word tago "day" is left out.

• la sepa de Oktobro 2026 – "7 October 2026"
• written: la 7-a de Oktobro 2026
• Hodiaŭ estas la unua de Majo. – "Today is the first of May."

When the date answers "when?", it takes -n: Ni venos la sepan de Oktobro – "We will come on 7 October". In letters: merkredon, la 26-an de Novembro 1997 (PMEG). Years are read as normal numbers: en 1887 = en mil okcent okdek sep. Month and weekday names are on days and months.

#Telling the time

Hours are ordinal numbers with la: "the third (hour)". Words like horo and minutoj are usually dropped (PMEG).

Use antaŭ "before" and post "after", never de. "At" a time is je (see prepositions).

#Examples in sentences

• Mi havas du fratojn kaj unu fratinon. – "I have two brothers and one sister."
• La bileto kostas dudek kvin eŭrojn. – "The ticket costs twenty-five euros."
• Mia avino naskiĝis en mil naŭcent kvindek kvar. – "My grandmother was born in 1954."
• Ŝi loĝas en la kvina etaĝo. – "She lives on the fifth floor."
• Mi legis la libron dufoje. – "I read the book twice."
• Duono de la klaso estas malsana. – "Half of the class is ill."
• La trajno foriras je la tria kaj duono. – "The train leaves at half past three."
• La infanoj eniris po du. – "The children came in two by two."

#Common questions

#How do you count to 10 in Esperanto?

Unu, du, tri, kvar, kvin, ses, sep, ok, naŭ, dek. Zero is nul.

#How do you say 2026 in Esperanto?

Du mil dudek ses. Thousands are always a separate word, so 2000 is du mil, not dumil.

#How do you say "first", "second" and "third"?

Add -a to the number: unua, dua, tria. "Twenty-first" is dudek-unua.

#What is a billion in Esperanto?

Miliardo (10⁹). Biliono means 10¹², because Esperanto follows the long scale.

#How do you tell the time in Esperanto?

Use la with an ordinal: Estas la oka – "It's eight o'clock". "At eight" is je la oka, and half past eight is la oka kaj duono.

#Sources

• Fundamento de Esperanto – grammar in English (rule 4)
• PMEG – Nombroj (numbers)
• PMEG – Forms of number words
• PMEG – O-word numbers (fractions, long scale)
• PMEG – A-word numbers (ordinals)
• PMEG – Hours
• PMEG – Dates
• PMEG – Mathematical expressions
• PMEG – Suffix OBL