Time Clauses | Esperanto Grammar

A time clause says when, while, before, after, since, or until another event happens. Esperanto time clauses are finite: they normally have their own subject and a verb with the tense or mood required by their meaning. Most importantly for English speakers, a real future event normally keeps -os even after kiam, ĝis, or another time linker.

Kiam locates an event or occasion

Use kiam when the subordinate event identifies the time of the main event:

Kiam mi alvenis hejmen, la infanoj jam dormis.

When I arrived home, the children were already asleep.

The arrival gives the time at which the sleeping situation held. The time clause may also follow the main clause:

La infanoj jam dormis, kiam mi alvenis hejmen.

The children were already asleep when I arrived home.

Initial position establishes a time frame before the main message. Final position often supplies the time afterward. The basic relation is the same, though context and information flow differ.

Kiam can also express repeated or general occasions:

Kiam mi laboras hejme, mi komencas la tagon pli frue.

When I work from home, I start the day earlier.

Here both present forms express a recurring pattern. Ĉiufoje kiam makes repetition explicit:

Ĉiufoje kiam la alarmo sonas, la hundo komencas boji.

Every time the alarm sounds, the dog starts barking.

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Think of an ordinary kiam clause as a fuller version of tiam: Kiam mi alvenis, ŝi foriris is approximately “At the time when I arrived, she left.”

Future time clauses use the future

English normally says “When I arrive, I will call,” using a present form after “when.” Esperanto directly marks both future events:

Kiam mi alvenos, mi telefonos al vi.

When I arrive, I will call you.

Telefonu al mi, kiam vi atingos la hotelon.

Call me when you reach the hotel.

The main command uses telefonu, while the later arrival uses atingos. Do not replace atingos with atingas merely because English uses “reach.” The Esperanto clause is free to show its own real future time.

The same rule holds with post kiam, antaŭ ol, and ĝis:

Post kiam ni finos la kunvenon, mi sendos la protokolon.

After we finish the meeting, I will send the minutes.

Mi ŝlosos la pordon antaŭ ol mi foriros.

I will lock the door before I leave.

This independence is part of the general Esperanto tense system, not an exceptional rule for time clauses. See tense in subordinate clauses for the wider contrast with English.

Kiam versus dum

Use dum when two situations extend through overlapping periods:

Dum mi kuiris, ŝi pretigis la tablon.

While I was cooking, she set the table.

The cooking continued while the table-setting took place. When both situations are durative, dum makes their overlap prominent:

Ni aŭskultis muzikon, dum la infanoj ludis en la ĝardeno.

We listened to music while the children played in the garden.

Use kiam for a point, occasion, or neutral temporal relation:

Kiam la telefono sonoris, mi kuiris.

When the phone rang, I was cooking.

The ringing is momentary; the cooking supplies the background. Dum la telefono sonoris would focus on the interval throughout which it kept ringing.

Do not combine the two linkers as dum kiam in an ordinary time clause. Choose the intended nuance:

dum mi loĝis en Romo — throughout the period of living there
kiam mi loĝis en Romo — at the time/period when I lived there

Dum can also develop a contrastive “whereas” meaning in more advanced prose, but its core temporal use is simultaneous duration.

Antaŭ ol and post kiam order events

The conventional forms are antaŭ ol “before” and post kiam “after”:

Kontrolu la horaron antaŭ ol vi mendos la biletojn.

Check the schedule before you order the tickets.

Post kiam la gastoj foriris, ni lavis la telerojn.

After the guests left, we washed the dishes.

The combinations are not symmetrical in form, but they are the established, easily understood choices. Antaŭ kiam is grammatically possible but uncommon, and post ol is theoretically possible but rare in practice. Bare antaŭ ke is not the neutral standard. For clear international prose, use antaŭ ol and post kiam.

When both clauses have the same understood subject, antaŭ ol + infinitive is a useful alternative:

Mi kontrolis la adreson antaŭ ol sendi la pakaĵon.

I checked the address before sending the parcel.

The understood subject of sendi is mi. If the subjects differ, keep the finite clause: Mi kontrolis la adreson antaŭ ol ŝi sendis la pakaĵon.

Ĝis marks an endpoint

A clause introduced by ĝis identifies the event at which the main situation ends:

Ni atendos ĉi tie, ĝis la pluvo ĉesos.

We will wait here until the rain stops.

The waiting continues up to the stopping of the rain. The endpoint should normally be a bounded change or event. If the intended endpoint is the beginning of sleep, say ekdormi:

Mi legis apud ŝi, ĝis ŝi ekdormis.

I read beside her until she fell asleep.

Mi legis ĝis ŝi dormis is poor because dormis describes a continuing state rather than the moment that ends the reading.

Do not add kiam after temporal ĝis:

Mi restos, ĝis vi revenos.

I will stay until you return.

Ĝis kiam is correct in a question, where it means “until what time”:

Mi demandis, ĝis kiam la muzeo restos malfermita.

I asked until what time the museum would remain open.

The first ĝis introduces a time clause; the second modifies interrogative kiam inside a reported question. The structures only look similar.

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Temporal ĝis already means “up to the event that follows.” Use ĝis vi revenos, not ĝis kiam vi revenos. Reserve ĝis kiam for a real question about the endpoint.

Do not add a negative after ĝis

Several languages use a negative-looking verb in an “until” clause even though the endpoint event eventually happens. Esperanto states that event positively:

Mi ne foriros, ĝis vi revenos.

I will not leave until you return.

The non-leaving ends when the return happens. Ĝis vi ne revenos would literally make nonreturn the endpoint and gives the wrong logic.

Compare a dum clause, where a genuine continuing negative is appropriate:

Mi restos ĉi tie, dum vi ne estos hejme.

I will stay here while you are not at home.

The negative state vi ne estos hejme lasts during the staying. Choose ĝis + positive endpoint or dum + continuing state according to the intended temporal shape.

De kiam marks a starting point

Use de kiam for a situation beginning at one event and extending afterward:

De kiam ni translokiĝis, mi piediras al la laboro.

Since we moved, I walk to work.

The move supplies the starting point; the walking habit continues in the present. For a completed past interval, both clauses can be past:

De kiam la projekto komenciĝis ĝis ĝi finiĝis, ŝi respondecis pri la buĝeto.

From when the project began until it ended, she was responsible for the budget.

English “since” can also mean “because.” Esperanto keeps the meanings separate: temporal de kiam versus causal ĉar.

Tuj kiam and temporal apenaŭ

Tuj kiam means “as soon as” and is neutral in speech and writing:

Tuj kiam mi ricevos la rezultojn, mi informos vin.

As soon as I receive the results, I will inform you.

— Kiam vi sciigos al ni la decidon? — Mi telefonos, tuj kiam la komisiono finos la kunvenon.

— When will you let us know the decision? — I will call as soon as the committee finishes the meeting.

Temporal apenaŭ can mean that the second event follows almost immediately after the first:

Apenaŭ ŝi malfermis la pordon, la hundo kuris eksteren.

As soon as she opened the door, the dog ran outside.

As a clause introducer, apenaŭ normally places its clause first. This use is somewhat more common in (formal) and (literary) narrative than in casual speech; tuj kiam is the transparent everyday alternative.

Clause order and punctuation

An initial time clause is commonly followed by a comma because it frames the main clause:

Kiam la vendejo malfermiĝos, ni aĉetos freŝan panon.

When the shop opens, we will buy fresh bread.

When the short time clause follows, punctuation depends on rhythm and how tightly it identifies the event. The crucial issue is not the comma but the visible linker and complete clause. Do not coordinate the events with kaj when one is intended to locate the other in time.

Common Mistakes

Copying English present tense for a future event

❌ Kiam mi alvenas morgaŭ, mi telefonos.

Incorrect for one future arrival — English uses present here, but Esperanto marks the future.

✅ Kiam mi alvenos morgaŭ, mi telefonos.

When I arrive tomorrow, I will call.

Combining dum and kiam

❌ Dum kiam mi laboris, li dormis.

Nonstandard redundancy — choose dum for overlapping duration.

✅ Dum mi laboris, li dormis.

While I worked, he slept.

Adding kiam after temporal ĝis

❌ Atendu ĉi tie, ĝis kiam mi revenos.

Incorrect as a plain time clause — ĝis already introduces the endpoint.

✅ Atendu ĉi tie, ĝis mi revenos.

Wait here until I return.

Adding a transferred negative after ĝis

❌ Mi ne komencos, ĝis vi ne donos signalon.

Wrong for the intended meaning — the endpoint is the giving of the signal.

✅ Mi ne komencos, ĝis vi donos signalon.

I will not begin until you give a signal.

Using an unbounded state as the endpoint

❌ Mi atendis, ĝis la infano dormis.

Poor endpoint choice — dormis describes an ongoing state.

✅ Mi atendis, ĝis la infano ekdormis.

I waited until the child fell asleep.

Key Takeaways

Use kiam for an occasion or time point, dum for overlapping duration, antaŭ ol and post kiam to order events, ĝis for an endpoint, and de kiam for a starting point. Give each finite time clause its semantically correct tense—including -os for a real future event. Use temporal ĝis without kiam or a transferred negative, and choose a bounded event such as ekdormi when the clause must mark an endpoint.

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