The future active infinitive presents its subject as about to perform, intending to perform, or destined to perform an action after the time of a governing verb. It consists of a future active participle plus esse: ventūrum esse “to be going to come.” Its two visible parts encode more than English “to”: the participle marks active voice, posteriority, gender, and number, while esse makes the phrase infinitival.
All unlabelled patterns below are standard Classical prose. Pedagogical examples mark vowel quantity; quoted source wording is reproduced without added macrons.
Formation and Agreement
Start from the supine or perfect passive participle stem, usually the fourth principal part, and add -ūrus, -ūra, -ūrum. Then use the form that agrees with the infinitive’s subject and add esse. In accusative-and-infinitive, that participle is accusative.
| Accusative subject | Future active infinitive | Meaning |
|---|---|---|
| eum | ventūrum esse | that he will come |
| eam | ventūram esse | that she will come |
| id | ventūrum esse | that it will come |
| eōs | ventūrōs esse | that they (masculine) will come |
| eās | ventūrās esse | that they (feminine) will come |
| ea | ventūra esse | that they (neuter) will come |
Sciō Mārcum crās ventūrum esse.
I know that Marcus will come tomorrow.
Sciō Iūliam crās ventūram esse.
I know that Julia will come tomorrow.
The long ū belongs to the suffix. The stem can be irregular: agō gives āctūrum esse, ferō gives lātūrum esse, eō gives itūrum esse, and sum gives futūrum esse. Because principal parts are lexical information, no rule can reliably predict every stem.
Posterior Relative Time
The future infinitive locates its event later than the governing verb, not necessarily later than the moment of speech. A present report points forward from the present; a past report points forward from a past viewpoint. The larger sequence is mapped on Tense Relations in Infinitives.
Lūcia dīcit sē librum lēctūram esse.
Lucia says that she will read the book.
Lūcia dīxit sē librum lēctūram esse.
Lucia said that she would read the book.
Latin does not change lēctūram esse. English normally uses “will” after a present reporting verb and “would” after a past one. That English backshift must not be mistaken for a Latin conditional: the Latin form is still a future infinitive expressing posteriority.
Compare all three relative times:
| Latin | Time relative to dīcit | Idiomatic English |
|---|---|---|
| dīcit eum venīre | simultaneous | he says that he is coming |
| dīcit eum vēnisse | anterior | he says that he came / has come |
| dīcit eum ventūrum esse | posterior | he says that he will come |
Putābāmus nāvēs ante hiemem reditūrās esse.
We thought that the ships would return before winter.
The feminine plural reditūrās agrees with nāvēs. It does not agree with the speaker represented by putābāmus.
Active Voice, Intention, and Prediction
The infinitive’s subject performs the future action. Context decides whether the prediction suggests intention, readiness, destiny, or merely later time. Latin does not require a separate auxiliary for each English nuance.
Mīlitēs iūrāvērunt sē urbem dēfēnsūrōs esse.
The soldiers swore that they would defend the city.
Medicī spērant puerum mox domum reditūrum esse.
The doctors hope that the boy will soon return home.
In the oath, intention is prominent; in the medical judgment, prediction is prominent. The same morphology works in both because its core contribution is active posteriority. The accusative sē in the first example refers back to plural mīlitēs, so the participle is masculine plural dēfēnsūrōs.
Deponent verbs form the future active participle normally and keep active meaning: profectūrum esse “to be going to set out,” secūtūram esse “to be going to follow,” moritūrōs esse “to be going to die.” Their future infinitives are much less visually exceptional than their perfect infinitives.
Explōrātor nūntiāvit hostēs prīmā lūce profectūrōs esse.
The scout reported that the enemy would set out at dawn.
Fore and Omission of Esse
The future infinitive of sum is futūrum esse, often shortened to fore. Both are normal Classical Latin; fore is especially common in compact prose (formal/literary).
Spērō fore ut mox pāx fīat.
I hope that peace will soon be made.
Here fore ut introduces a result-like clause with a subjunctive and supplies a future equivalent when a participial future infinitive is awkward or unavailable. With a present governing verb, the subjunctive is normally present (fiat); after a past governing verb, it normally shifts to imperfect (fieret): spērābam fore ut pāx fieret. This is a productive prose alternative, not a literal word-for-word match to English “will.”
Authors may omit esse after a future participle when the infinitival construction is already clear, especially in sustained indirect discourse (literary). A phrase such as dīxit sē ventūrum therefore still means “he said that he would come.” Learners should include esse in their own early prose.
Livy opens his preface by wondering, facturusne operae pretium sim, whether he is going to accomplish something worthwhile. This source-faithful finite phrase is not a future infinitive, but it shows that -ūrus carries prospective meaning independently of esse. In indirect statement, the corresponding masculine singular accusative would be factūrum esse.
Verbs Without a Supine Stem
The regular future active infinitive depends on a future active participle, and that participle normally depends on a supine stem. If a verb lacks such a stem, Classical prose often uses fore ut + subjunctive rather than inventing a form. Even where a participle exists, fore ut can avoid cumbersome agreement or emphasize the future occurrence of a whole clause.
This limitation matters in production. An English future does not license attaching -ūrum esse directly to a present stem. Check the principal parts, then choose either a genuine participle or the fore ut construction.
Common Mistakes
Using a nominative participle in indirect statement
❌ Sciō Iūliam ventūra esse.
Incorrect — ventūra is nominative feminine singular.
✅ Sciō Iūliam ventūram esse.
I know that Julia will come.
Making the participle agree with the reporting subject
❌ Putāmus nāvēs reditūrōs esse.
Incorrect — masculine reditūrōs does not agree with feminine nāvēs.
✅ Putāmus nāvēs reditūrās esse.
We think that the ships will return.
Translating a past report with English “will” automatically
❌ Dīxit sē ventūrum esse. ‘He said that he will come.’
Usually incorrect in ordinary English sequence of tenses.
✅ Dīxit sē ventūrum esse.
He said that he would come.
Confusing future active and future passive
❌ Nūntiat urbem captūram esse, meaning ‘He reports that the city will be captured.’
Incorrect — captūram makes the city the future captor.
✅ Nūntiat urbem captum īrī.
He reports that the city will be captured.
Key Takeaways
- Form the future active infinitive with an agreeing future active participle plus esse.
- It marks an active event posterior to the governing verb; English “will” versus “would” depends on context.
- In indirect statement, the participle is accusative and agrees with the embedded subject.
- Use genuine principal parts; where no future participle is available, fore ut plus subjunctive provides a Classical alternative.
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Start learning Latin →Related Topics
- Perfect Passive InfinitiveA2 — How participial agreement and esse express an event already undergone by the infinitive's subject.
- Future Passive InfinitiveA2 — How the rare Latin construction in supine -um plus īrī marks an event to be undergone later.
- Perfect Active InfinitiveA2 — How the Latin perfect active infinitive marks an active event anterior to its governing verb, especially in indirect statement.
- Accusative Subject of the InfinitiveA2 — Recognize the accusative noun or pronoun that serves as the subject inside a Latin infinitival clause.