Esperanto often marks a calendar date with -n because the date is a temporal complement answering “on what date?” The familiar form la dek-kvaran de Oktobro is short for la dek-kvaran tagon de Oktobro. The ending is not part of the date itself: when the same date is a subject or follows a preposition, its case changes with its role.
All patterns below are neutral standard Esperanto. Fully written dates occur in conversation and prose; compact numerical formats are mainly (formal) or technical conventions.
A date answering “when?” takes temporal -n
Accusative -n has several functions beyond direct objects. One is marking a point in time. A calendar date used as the time of an event therefore commonly appears as an accusative temporal complement.
La kurso komenciĝos la dek-kvaran de Oktobro.
The course will begin on the fourteenth of October.
Ni geedziĝis la trian de Junio 2022.
We got married on the third of June 2022.
The day number is an ordinal adjective: dek-kvara, tria, dudek-unua. The noun tagon is normally understood and omitted, but the ordinal keeps the endings that it would have beside that noun. Thus la dek-kvaran is not an object; it is an elliptical accusative time phrase.
La ekspozicio malfermiĝos la unuan tagon de Majo.
The exhibition will open on the first day of May.
La ekspozicio malfermiĝos la unuan de Majo.
The exhibition will open on the first of May.
These two sentences have the same temporal structure. The second simply leaves tagon unspoken. The month follows de and therefore remains Majo, without -n.
Writing the day number
When written in words, use the ordinary ordinal: la dudek-duan de Februaro. With digits, Esperanto normally shows the grammatical endings after a hyphen: la 22-an de Februaro. The -a makes the number ordinal; -n marks the date's temporal role.
| Role | Written out | With digits |
|---|---|---|
| date as subject | la dudek-dua de Februaro | la 22-a de Februaro |
| date answering “when?” | la dudek-duan de Februaro | la 22-an de Februaro |
| after a preposition | ĝis la dudek-dua de Februaro | ĝis la 22-a de Februaro |
Ĉu vi estos libera la 22-an de Februaro?
Will you be free on February 22?
Ne, sed mi povos veni la 23-an.
No, but I'll be able to come on the twenty-third.
The year may follow the month directly when the structure is clear: la 3-an de Junio 2022. A fuller form is la 3-an de Junio de la jaro 2022. The year does not copy -n from the omitted tagon; it identifies the year within the date.
Following this guide’s PMEG-aligned house style, month names are treated as proper names and capitalized: Januaro, Februaro, Marto. Lowercase forms such as januaro are widespread in contemporary writing and immediately understandable; this is attested orthographic variation, not a different case pattern.
The same date without -n
A date is not inherently accusative. If it is the subject of esti or another clause, it appears without -n. A predicate expression identifying the date is also unmarked.
La dek-kvara de Oktobro estas lundo.
The fourteenth of October is a Monday.
La fina limdato estas la tridek-unua de Marto.
The final deadline is March thirty-first.
Compare the minimal contrast:
La unua de Septembro estas la unua lerneja tago.
September first is the first school day.
La lernejo remalfermiĝos la unuan de Septembro.
The school will reopen on September first.
The first la unua is the subject. The second answers kiam? and takes temporal -n. Word position does not decide the case: the date's clause role does.
A preposition replaces temporal -n
A preposition can mark the date's relationship explicitly. After ordinary prepositions, do not also add temporal -n. This creates a useful contrast between la 10-an “on the tenth” and ĝis la 10-a “until the tenth.”
La oficejo estos fermita de la 24-a de Decembro ĝis la 2-a de Januaro.
The office will be closed from December 24 until January 2.
Ni prokrastis la decidon ĝis la dek-kvina de Aŭgusto.
We postponed the decision until the fifteenth of August.
In these examples, de and ĝis already mark the role of their complements. The ordinals remain in -a, not -an. This is the same general principle explained on the page about prepositional complements.
The preposition je can also introduce a time point, but modern usage normally reserves je la sepa for clock time. Without an expressed unit, la sepan is naturally understood as the seventh day of a month, while je la sepa is naturally understood as seven o'clock.
La intervjuo okazos la sepan de Aprilo je la sepa vespere.
The interview will take place on April seventh at seven in the evening.
Weekdays and dates
A weekday noun with -n can mark one specific, contextually known day: lundon, venontan vendredon, tiun sabaton. This is the same time-point use, even when the article is absent.
Ni ricevis la pakaĵon vendredon la 12-an de Julio.
We received the package on Friday, July 12.
Mi ne laboros venontan lundon, ĉar la oficejo estos fermita.
I won't work next Monday because the office will be closed.
The adverb lunde can mean “on Monday” and often has a more general or scheduling flavor. Ĉiulunde unambiguously means every Monday. By contrast, lundon readily identifies a particular Monday supplied by context. Actual usage allows overlap, so this is a meaning tendency rather than an absolute rule.
La teamo ordinare kunvenas lunde, sed ĉi-foje ni kunvenos mardon.
The team normally meets on Mondays, but this time we'll meet on Tuesday.
Letter headings and standalone date lines
At the beginning of a letter or notice, a standalone date is traditionally treated as an implicit temporal complement and can take -n: Lyon, la 12-an de Majo 2026. This is established (formal) usage even though no full sentence is written.
Compact forms such as 12.05.2026 or the international 2026-05-12 do not visibly show Esperanto case. They are formatting systems rather than fully inflected phrases. In running prose, the expanded la 12-an de Majo 2026 makes the syntax and month unmistakable across different national date-order conventions.
Parizo, la 12-an de Majo 2026
Paris, May 12, 2026
Common Mistakes
Treating the ordinal as a cardinal number
❌ La kunveno okazos la dek kvar de Majo.
Incorrect — the day of the month is an ordinal with -a, and the temporal phrase needs -n.
✅ La kunveno okazos la dek-kvaran de Majo.
The meeting will take place on May fourteenth.
Adding -n to the month after de
❌ Ni alvenos la 6-an de Junion.
Incorrect — de already marks the month's role.
✅ Ni alvenos la 6-an de Junio.
We will arrive on June sixth.
Assuming every mention of a date is accusative
❌ La 1-an de Januaro havas dudek kvar horojn.
Incorrect — here the date itself is the subject of havas.
✅ La 1-a de Januaro havas dudek kvar horojn.
January first has twenty-four hours.
Keeping temporal -n after a preposition
❌ La rabato validas ĝis la 30-an de Novembro.
Incorrect — the complement of ĝis remains without -n.
✅ La rabato validas ĝis la 30-a de Novembro.
The discount is valid until November thirtieth.
Confusing a date with a clock time
❌ Ni renkontiĝu la okan vespere.
Incorrect for ‘at eight’ — without je, la okan normally suggests the eighth day.
✅ Ni renkontiĝu je la oka vespere.
Let's meet at eight in the evening.
Key Takeaways
- A date answering “when?” commonly takes temporal -n: la 14-an de Oktobro.
- The day number is an ordinal modifying an understood tagon; the month after de remains unmarked.
- A date used as subject or predicate has no -n, and a date after an ordinary preposition follows that preposition without temporal -n.
- Use je la oka for eight o'clock, but la okan for the eighth day when the context supplies the month.
Related Topics
- The Accusative -N: OverviewA1 — Understand how Esperanto uses final -n to mark direct objects, direction, time, and measurement without relying on word order.
- Time DurationA1 — Express how long an event lasts by marking a time measure with -n or by using an explicit duration phrase.
- Dates and YearsA2 — Form, inflect, write, and read Esperanto calendar dates and years without importing ambiguous English date order.
- Days, Months, and SeasonsA2 — Use Esperanto weekday, month, and season names with the right capitalization, article, preposition, adverb, and temporal case.
- Ordinal NumbersA1 — Form and use Esperanto ordinal numbers for sequence, labels, dates, clock hours, and ranked noun phrases.
- JeB1 — Use je for conventional clock-time, measure, body-part, and abstract relations when no more specific preposition expresses the intended role.