Futur Simple: Irregular Stems

The futur simple endings — -ai, -as, -a, -ons, -ez, -ont — are universal: they attach to every verb in French, regular or irregular. What changes from verb to verb is the stem. For most verbs the stem is the infinitive (or, for -re verbs, the infinitive minus the final -e). For about twenty high-frequency verbs the stem is something else entirely. Être gives ser-; avoir gives aur-; aller gives ir-. These stems have to be memorized.

The good news: the irregular stems all end in -r- (so the universal -r- before the ending is preserved), and once you learn them for the futur simple, you have them for the conditional too — same stem, different endings. This page lists every common irregular stem, gives the complete je-tu-il-nous-vous-ils paradigm for the most important ones, and groups them by the patterns that make them easier to remember.

Why these verbs are irregular

The futur simple stem of regular verbs is the infinitive because the tense originated as infinitive + avoir: Vulgar Latin cantare habeo "I have to sing" → Old French chanterai "I will sing." For most verbs that fusion preserved the infinitive intact. But for some high-frequency verbs — exactly the verbs you use most often — phonetic erosion or analogy reshaped the stem into something shorter or different.

The result is a list of irregular stems that you have to memorize but that, once memorized, are highly stable: every form of the futur simple uses the same stem, every form of the conditional uses the same stem, and the endings never change. Memorize the stem once and you have ten conjugated forms — six futur simple, six conditional, minus duplicates of the r-.

The complete list of irregular stems

That is roughly the complete inventory. Most compounds inherit the irregular stem from the base verb: revenir → reviendr-, devenir → deviendr-, retenir → retiendr-, contenir → contiendr-, revoir → reverr-. The notable exception is prévoir (to foresee, to plan), which does not follow voir: its futur stem is prévoir-, giving je prévoirai — not préverr-. Pourvoir (to provide) behaves the same way: je pourvoirai.

Full paradigms for the high-frequency verbs

être (to be) — stem ser-

The stem ser- has nothing visibly to do with être — it descends from a separate Latin root (essere → ser-), the same root that gives Spanish ser. This is one of the most fundamental irregular stems and absolutely has to be memorized cold.

avoir (to have) — stem aur-

The futur antérieur of every avoir-auxiliary verb is built on this stem: j'aurai mangé, tu auras fini, nous aurons compris. Master aurai and you can then build the entire futur antérieur paradigm of avoir-verbs.

aller (to go) — stem ir-

The stem ir- descends from a different Latin verb: ire (to go), the same root that gives English itinerary. Aller in modern French is a suppletive paradigm — pieces from three different Latin verbs (ambulare → aller, vadere → vais, ire → irai) glued into one verb. The futur uses the ire piece.

faire (to do, to make) — stem fer-

Note the spelling: fer- with one r. Don't confuse with ferr- (which would be incorrect).

voir (to see) — stem verr-

Two r*s in *verr-. The double r shows up in pronunciation: verrai /vɛʁe/ has a slightly more emphatic r than the regular pattern. The same applies to pourr-, courr-, mourr-, enverr- below.

pouvoir (to be able to) — stem pourr-

vouloir (to want) — stem voudr-

The conditional of vouloir — je voudrais (I would like) — is the polite-request workhorse of French. Same stem, different endings.

devoir (to have to) — stem devr-

savoir (to know) — stem saur-

venir / tenir — stems viendr- / tiendr-

All compounds of venir (revenir, devenir, parvenir, prévenir, intervenir, convenir) and tenir (retenir, contenir, soutenir, maintenir, obtenir, appartenir) follow the same stem pattern: je reviendrai, je deviendrai, je retiendrai, j'obtiendrai.

courir / mourir / envoyer — double-r stems

The doubled r is mandatory in spelling and audible in pronunciation. Don't lose it.

Impersonal verbs: falloir, pleuvoir, valoir

These verbs only appear in the third-person singular (and sometimes plural for valoir):

Il faudra is one of the most useful future forms in French — equivalent to "it will be necessary," "we'll need to," "you'll have to."

recevoir — stem recevr-

The other -cevoir verbs follow the same pattern: apercevoir → j'apercevrai, concevoir → je concevrai, décevoir → je décevrai.

Patterns to make memorization easier

The irregular stems aren't entirely random. A few patterns help:

-dr- stems for verbs of motion / will / state

Venir → viendr-, tenir → tiendr-, vouloir → voudr-, devoir → devr-, falloir → faudr-, valoir → vaudr-. These all insert a d before the r. If you remember "verbs about coming, holding, wanting, owing, needing, being worth take -dr-," you have six stems at once.

Doubled-r stems

Voir → verr-, pouvoir → pourr-, courir → courr-, mourir → mourr-, envoyer → enverr-. Five verbs with doubled r. The r is audibly emphatic in speech.

Suppletive stems

Être → ser- and aller → ir- are not derived from their infinitives at all. They come from separate Latin roots. Just memorize them.

-aur- in avoir, -aur- in savoir

Avoir → aur- and savoir → saur- both have the -aur- sequence. A small mnemonic.

Same stem, two tenses: futur and conditional

Every irregular futur stem is also the irregular conditional stem. The conditional uses imparfait endings (-ais, -ais, -ait, -ions, -iez, -aient) on the same stem:

The je forms of futur and conditional differ only in -ai /e/ versus -ais /ɛ/. Many regional varieties of French don't distinguish these vowels clearly, so context disambiguates. Pay attention to the ending consonant in tu / nous / ils forms: futur has no -s; conditional always has -s. Tu auras (futur) versus tu aurais (conditional). One letter, very different meanings.

Pronunciation notes

The irregular stems are short, often monosyllabic, and the -e- of the stem tends to drop in casual speech: serai → /sʁe/, ferai → /fʁe/, aurai → /oʁe/, verrai → /vɛʁe/, pourrai → /puʁe/. The -r- is always pronounced — even when the stem reduces phonetically, the -r- survives.

Comparison with English

English future is built with will + base form, with no irregular stems on the verb side. English speakers may instinctively look for the same regularity in French and produce je voirai (treating the infinitive voir as the stem). The fix is simply to memorize the twenty or so irregular stems above. A second friction point: the conditional of vouloir, pouvoir, devoir is enormously common in polite French (je voudrais, je pourrais, je devrais) — once you have je voudrais, you have je voudrai for free.

Common Mistakes

Mistake 1: Building futur of être from the infinitive.

Mistake 2: Building futur of aller from the infinitive.

Mistake 3: Single r in verr- / pourr- / courr-.

Mistake 4: Forgetting the d in viendr- / tiendr- / voudr- / faudr-.

Mistake 5: Mixing futur and conditional endings.

Mistake 6: Treating prévoir as irregular like voir.

Key takeaways

About twenty high-frequency French verbs have irregular futur simple stems: être → ser-, avoir → aur-, aller → ir-, faire → fer-, voir → verr-, savoir → saur-, pouvoir → pourr-, vouloir → voudr-, devoir → devr-, recevoir → recevr-, venir → viendr-, tenir → tiendr-, courir → courr-, mourir → mourr-, envoyer → enverr-, falloir → faudr-, pleuvoir → pleuvr-, valoir → vaudr-. The endings remain the regular set, and every stem ends in -r-. Compounds inherit from the base verb (revenir, devenir, retenir, obtenir all use -iendr-).

These same stems double as the conditional stems. Once you have memorized je serai, you also have je serais; once you have j'aurai, you also have j'aurais. Twenty stems give you forty conjugated forms across two tenses, plus all the compounds — one of the most leveraged pieces of French verb morphology.