Esperanto infinitives behave partly like verbs and partly like noun-like phrases. They can follow a small set of prepositions directly, but not every English preposition-plus-ing construction maps to a preposition plus -i. The established core is por fari, anstataŭ fari, and krom fari; modern sen fari is also widespread, while many other combinations require a different structure.
Here -i is the invariant, tenseless verb ending. If you replace an infinitive with a full clause, that clause needs an expressed subject where necessary and a finite verb in -as, -is, -os, -us, or -u. Those endings mark tense or mood, never the subject's person or number; this is why por ke la gastoj eniru uses -u, while antaŭ ol la gastoj alvenos uses future -os.
Purpose with por + infinitive
Por introduces the purpose of the main action. The understood subject of the infinitive is normally the subject of the main verb.
Mi iris al la vendejo por aĉeti lakton.
I went to the shop to buy milk.
Ni malfermis la fenestrojn por aerumi la ĉambron.
We opened the windows to air the room.
Ŝi telefonis por konfirmi la rezervon.
She called to confirm the reservation.
— Kial vi venis tiel frue? — Por helpi prepari la salon.
— Why did you come so early? — To help prepare the hall.
In each sentence, the person who goes, opens, or calls also buys, airs, or confirms. The infinitive remains verb-like and takes its own object: lakton, la ĉambron, la rezervon.
When the purpose action has a different subject, use por ke plus volitive -u.
Mi malfermis la pordon, por ke la gastoj eniru.
I opened the door so that the guests could enter.
Mi skribis la adreson klare, por ke vi povu trovi la domon.
I wrote the address clearly so that you could find the house.
The comma before por ke is common and helps show the clause boundary. The important grammatical distinction is the finite subordinate subject la gastoj or vi.
Replacement with anstataŭ + infinitive
Anstataŭ presents one action as replacing another. This is a foundational, fully standard combination.
Anstataŭ telefoni, ŝi sendis mallongan mesaĝon.
Instead of calling, she sent a short message.
Li plendis dum horo anstataŭ proponi solvon.
He complained for an hour instead of proposing a solution.
The understood actor of the infinitive is normally the actor of the contrasting main action: she would have called; he could have proposed. If the subjects differ, use a full clause so that both actors are visible.
Anstataŭ tio, ke la administranto respondu, lia asistanto sendis mallongan klarigon.
Instead of the manager responding, his assistant sent a short explanation.
This finite pattern is less compact but prevents a false same-subject reading.
Exception or addition with krom + infinitive
Krom can mean “besides” or “except for.” With an infinitive, context and the larger sentence determine whether the action is added or excluded.
Krom studi, ŝi laboras dudek horojn semajne.
Besides studying, she works twenty hours a week.
Ni povis fari nenion krom atendi.
We could do nothing except wait.
Li ne faris multon krom reorganizi la dosierojn.
He did not do much besides reorganizing the files.
The construction is fully standard. Notice that atendi remains an infinitive after povis and krom; it does not take tense or accusative marking.
Sen + infinitive: modern accepted usage with history
Sen fari means “without doing.” Traditional prescriptive sources treated sen + infinitive as faulty, and Zamenhof criticized it, although examples also occur in his own usage. In contemporary Esperanto it is frequent, transparent, and broadly accepted.
Its understood actor normally comes from the surrounding clause, most often its subject: in ŝi eliris sen diri adiaŭ, the person who leaves is also the person who does not say goodbye.
Ŝi eliris sen diri adiaŭ.
She left without saying goodbye.
Mi ne povas legi tion sen ridi.
I cannot read that without laughing.
Li respondis sen rigardi min.
He answered without looking at me.
This is accepted modern usage. In conservative or deliberately traditional prose, alternatives remain available: an action noun after sen, or a negative adverbial participle.
Ŝi eliris sen adiaŭo.
She left without a goodbye.
Ne rigardante min, li respondis.
Without looking at me, he answered.
The participial version explicitly presents a simultaneous circumstance and shares the main subject. The noun version packages the omitted event as a thing.
Antaŭ ol + infinitive, not bare antaŭ
Before an infinitive, temporal antaŭ conventionally combines with ol. The main clause and infinitive normally share a subject.
Antaŭ ol foriri, bonvolu malŝalti la lumojn.
Before leaving, please turn off the lights.
Mi relegis la mesaĝon antaŭ ol sendi ĝin.
I reread the message before sending it.
If subjects differ, use a full clause with antaŭ ol.
Ni manĝos antaŭ ol la gastoj alvenos.
We will eat before the guests arrive.
Bare antaŭ foriri is not the established construction. Here ol is not optional decoration; antaŭ ol jointly introduces the reduced time clause.
Avoid post, dum, and ĝis directly before an infinitive
Traditional and recommended Esperanto does not normally say post fari, dum fari, or ĝis fari. Choose a structure that makes the temporal relation explicit.
For “after doing,” use an -inte adverbial participle, post kiam plus a finite clause, or post plus an action noun.
The adverbial participles page explains the same-subject -ante and -inte alternatives in depth.
Fininte la raporton, mi sendis ĝin al la teamo.
After finishing the report, I sent it to the team.
Post kiam mi finis la raporton, mi sendis ĝin al la teamo.
After I finished the report, I sent it to the team.
Post la fino de la kunveno, ĉiuj iris hejmen.
After the end of the meeting, everyone went home.
For “while doing,” use an -ante participle or dum plus a finite clause.
Aŭskultante la podkaston, mi kuiris vespermanĝon.
While listening to the podcast, I cooked dinner.
Mi kuiris, dum la infanoj faris siajn taskojn.
I cooked while the children did their homework.
For “until doing,” use ĝis plus a finite clause: Mi atendis, ĝis ŝi respondis. The endpoint normally needs its own subject and tense.
Other English prepositions often require restructuring
English freely uses “about doing,” “by doing,” “despite doing,” and similar forms. Esperanto often chooses an action noun, a participle, or a finite clause rather than placing that preposition before an infinitive.
| Intended relation | Recommended Esperanto |
|---|---|
| about doing | pri farado, or a verb that directly takes fari |
| by doing | an -ante participle, or per farado |
| despite doing | kvankam ... or malgraŭ tio, ke ... |
| after doing | an -inte participle or post kiam ... |
Ni parolis pri translokiĝo al alia oficejo.
We talked about moving to another office.
Ŝi solvis la problemon ŝanĝante unu agordon.
She solved the problem by changing one setting.
The exact choice depends on whether you want to package the activity as a noun, show simultaneous action, or state a full proposition. There is no honest one-rule translation for every English preposition plus -ing.
Combinations such as post enlitiĝi, dum promeni, and pri lerni have become more visible since about 2000, especially among younger speakers. They are intelligible and represent an emerging usage, but many speakers still find them strange or incorrect. For neutral or formal Esperanto—and as a reliable learner default—prefer post kiam or -inte, dum plus a finite clause or -ante, and pri plus an action noun. The rejected forms in the Common Mistakes section below therefore represent the traditional and still recommended norm, not a claim that no speaker ever uses them.
Quoted infinitives are different
Any preposition can stand before an infinitive when the infinitive is being mentioned as a word or as the name of an action rather than directly integrated into ordinary clause syntax.
Inter voli kaj fari estas granda diferenco.
There is a big difference between wanting and doing.
Here inter relates the named concepts “wanting” and “doing.” This special metalinguistic pattern does not license unrestricted combinations such as dum manĝi in an ordinary sentence.
Common Mistakes
Using por when the actors differ
❌ Mi lasis la pordon malfermita por la kato eniri.
Incorrect in careful Esperanto — the infinitive cannot simply take la kato as a new subject.
✅ Mi lasis la pordon malfermita, por ke la kato eniru.
I left the door open so that the cat could enter.
Omitting ol after temporal antaŭ
❌ Antaŭ foriri, mi kontrolis la adreson.
Incorrect — the established reduced time construction is antaŭ ol + infinitive.
✅ Antaŭ ol foriri, mi kontrolis la adreson.
Before leaving, I checked the address.
Using post + infinitive
❌ Post fini la laboron, ni iris por trinki ion.
Incorrect in the traditional standard — use an -inte participle or a full clause.
✅ Fininte la laboron, ni iris por trinki ion.
After finishing the work, we went to have something to drink.
Using dum + infinitive
❌ Mi aŭskultis muzikon dum kuiri.
Incorrect — express same-subject simultaneity with an -ante participle.
✅ Mi aŭskultis muzikon kuirante.
I listened to music while cooking.
Copying English “about” before an infinitive
❌ Ni diskutis pri aĉeti novan aŭton.
Incorrect in recommended usage — pri normally takes an action noun, not an infinitive.
✅ Ni diskutis pri aĉeto de nova aŭto.
We discussed buying a new car.
Key Takeaways
- The fully established core is por, anstataŭ, and krom plus an infinitive.
- Sen + infinitive is historically disputed but common and accepted in contemporary usage.
- Use antaŭ ol + infinitive; for post and dum, prefer participles, full clauses, or action nouns.
- A changed subject normally requires a finite clause such as por ke ... -u.
- English preposition-plus-ing patterns must be translated by meaning, not mechanically.
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Start learning Esperanto →Related Topics
- The Infinitive in -IA1 — Use the invariant -i form to name an action or state without asserting tense, person, or mood.
- Subject Control with InfinitivesA2 — Identify the understood actor of an infinitive after same-subject, influence, perception, causative, and purpose constructions.
- PorB2 — Use por for an intended beneficiary, purpose, use, result, exchange, or the goal toward which an action is directed.
- AnstataŭA2 — Use anstataŭ to replace one person, thing, role, or action with another while preserving the contrasted role clearly.
- KromB1 — Use krom to set one item apart, then read polarity and ankaŭ to distinguish exception from addition.
- SenB2 — Use sen for absence, including common sen + infinitive constructions and careful handling of negative scope.