Telling the Time and Dates in Esperanto: je la tria, la unuan de marto

Time expressions are the chapter where the course stops teaching you things separately and starts asking you to use them together. A clock time is an ordinal number. A date is an ordinal number plus a preposition. On Monday is an accusative. Before you leave is a preposition wearing a disguise. Nothing here is new; the assembly is.

What time is it

The question is Kioma horo estas? - literally the how-manyeth hour is it?, built from kiom with the adjective ending, which is exactly the sort of thing the correlatives let you do.

The answer is la plus an ordinal:

Estas la tria. - It is three o'clock.

Horo is usually dropped, because la tria already means the third hour and nothing else is competing for the slot. Say estas la tria horo if you like; nobody will mind, and nobody will bother.

To say at a time, use je:

Mi venos je la tria. - I will come at three.

Je is the preposition Esperanto keeps for jobs no other preposition claims, and clock time is its most-used one. The prepositions article has the rest of its territory.

Minutes, halves and quarters

Minutes go on with kaj:

One warning, aimed at the Germans and the Dutch in the room. La tria kaj duono is half past three, not half past two. Esperanto counts forward from the hour that has already struck, the English way, rather than reaching towards the hour ahead the way halb vier does. Zamenhof had to pick one, he picked this one, and the alternative is not an option you have.

For anything official - timetables, meeting invitations, radio - use the 24-hour clock and read the number straight:

La kunveno komenciĝos je la dek-kvina horo. - The meeting starts at 15:00.

Tagmezo is noon and noktomezo is midnight, and both take je: je tagmezo. The parts of the day work best as adverbs: matene, vespere, nokte - in the morning, in the evening, at night.

Dates

An ordinal, de, and the month:

la unua de marto - the first of March

Months and weekdays are ordinary common nouns in Esperanto, so they get no capital letter. marto, aprilo, lundo, dimanĉo. English capitalises them out of habit rather than logic, and Esperanto declined to copy the habit.

Written with digits, the ordinal ending hyphenates onto the numeral: la 1-a de marto, la 23-a de septembro.

The full weekday-and-date form runs largest-last, like the spoken version:

lundo, la 2-a de septembro 2026

Years are one number

This is short and it matters. A year in Esperanto is read as a single cardinal number:

English chops a year into two two-digit halves and says eighteen eighty-seven. Esperanto has no such convention, and a learner who imports it says something a listener has to stop and unpick. En puts you inside the year: en 1887, or en la jaro 1887 when you want to be unmistakable. Centuries use the ordinal: la dudeka jarcento.

The accusative of time

Here is the piece that makes English speakers happiest once it lands.

The accusative -n does more than mark direct objects. Put it on a time word and the word becomes an adverbial saying when or for how long, with no preposition needed at all:

Mi laboris la tutan tagon. - I worked all day.

Li restis en la urbo tri tagojn. - He stayed in town for three days.

Ni komencos la unuan de marto. - We will begin on the first of March.

You may reasonably worry that this collides with the direct object. It does not, in practice: a verb takes one direct object, and no listener has ever wondered whether you ate a Monday. Where a sentence really is ambiguous, reach for dum or en instead and the problem evaporates.

The same trick handles measure generally - ĝi kostas dek eŭrojn, li kuris kvin kilometrojn - but time is where you will use it every day.

dum, antaŭ ol, post kiam

Now the bit that gets written wrong most often.

Antaŭ and post are prepositions. A preposition takes a noun phrase. It cannot swallow a whole clause with its own subject and verb:

antaŭ la milito - before the war

post la vespermanĝo - after dinner

To put a clause after them, you need a converter, and each takes a different one:

Antaŭ ol li venis, mi dormis. - Before he came, I was asleep.

Post kiam ŝi finis la libron, ŝi skribis leteron. - After she finished the book, she wrote a letter.

Dum mi laboris, la knabo dormis. - While I was working, the boy slept.

Antaŭ ke and post ke are both wrong, and both are extremely common in beginners' writing because English uses one word for each job. Dum and ĝis happen to work either way unaided, which is a small mercy and also the reason people assume the other two do too.

Antaŭ ol also takes a bare infinitive when the subject is the same in both halves, and it is neater that way:

Antaŭ ol foriri, li dankis nin. - Before leaving, he thanked us.

One last trap, because it is a good one. With a quantity, antaŭ means ago and post means from now, and neither takes the accusative:

Li venis antaŭ tri tagoj. - He came three days ago.

Li venos post tri tagoj. - He will come in three days.

Compare li restis tri tagojn, he stayed for three days. The -n marks duration; the preposition marks distance from now. Get those two confused and you have moved an event a week.

What to take away

• Clock time is la plus an ordinal, and je for at: je la tria.
• La tria kaj duono is 3:30, counting forwards.
• Dates are ordinal + de + lowercase month: la unua de marto.
• Years are one cardinal: mil okcent okdek sep.
• The accusative marks when and how long: lundon, la tutan tagon, tri tagojn.
• antaŭ ol and post kiam before a clause; antaŭ tri tagoj for ago.