Бути: The Complete Picture

The verb бути "to be" is at once the most important verb in Ukrainian and the one you will most often not say. In the present tense it is largely invisible: where English needs "is / am / are," Ukrainian usually leaves a gap — Він студе́нт is a complete sentence, literally "He student." Yet the verb is fully alive in the past and future, and it carries a grammatical surprise: the noun that names what someone is sits in the nominative in the present but flips to the instrumental in the past, future and infinitive — Він студе́нт but Він був студе́нтом. This page lays out бути tense by tense, explains the present/non-present case switch on the predicate, and covers the existential є and its negative нема́є.

Present: the missing verb and the survivor є

In a plain "X is Y" sentence in the present, Ukrainian inserts nothing. The subject and the predicate simply stand side by side, often with a dash in writing.

There is no Він є студе́нт in normal speech. The one form of present бути that survives is *є, and crucially it is invariant — the same є for all persons and numbers (я є, ти є, він є, ми є, вони́ є). You use it in three situations:

• existence / "there is": На сто́лі є хліб "There's bread on the table";
• possession, in the у + genitive construction: У ме́не є кни́жка "I have a book" (covered on the мати vs у мене є page);
• emphasis or contrast, in careful or formal style: Украї́на є незале́жною держа́вою "Ukraine is an independent state."

That last example previews the rule below: even the emphatic present є can pull the predicate into the instrumental in formal register (є осно́вою).

Past: був, була́, було́, були́

The past tense is fully formed and, unusually for Ukrainian, agrees in gender and number rather than person — there is one masculine form for "I/you/he was," one feminine, and so on. The forms are built on the stem бу-:

Future: бу́ду, бу́деш, бу́де… — and its double life

The future of бути conjugates fully by person:

These same forms do double duty. On their own they mean "will be" (Я бу́ду вдо́ма "I'll be home"). But placed before the infinitive of an imperfective verb, they form the analytic future: бу́ду чита́ти "I will read / will be reading." So бу́ду is both a full lexical verb and the future auxiliary — one paradigm, two jobs. The analytic future is treated in full on its own page.

The core pattern: predicate goes instrumental in the non-present

Here is the structural heart of бути. The noun (or adjective, optionally) that names what or who the subject is — the predicate — changes case depending on the tense:

• present (verb omitted): predicate is nominative — Він студе́нт. Вона́ лі́карка.
• past / future / infinitive / conditional (verb present): predicate is instrumental — Він був студе́нтом. Вона́ бу́де лі́каркою. Хо́чу бути письме́нником.

The logic: the instrumental marks a role you occupy through time rather than a permanent identity fused with the subject. When the linking verb actually appears, it pulls the predicate into the instrumental of "functioning as."

Imperative, infinitive, conditional

• Infinitive: бути — used after modal and desire verbs and to form predicate constructions: хо́чу бути, повине́н бути, ра́до б бути там.
• Imperative: будь! (sg.), бу́дьте! (pl./formal) — "be!"; common in wishes and set phrases.
• Conditional: був би / була́ б / було́ б / були́ б — "would be," the past form plus the particle би / б.

Negation of existence: нема́є + genitive

To say something is not present or does not exist, Ukrainian does not use не є. It uses the special impersonal negative *нема́є (also written нема́ in informal speech), and the thing that is absent goes into the genitive — the genitive of negation.

In the past and future the same logic applies with не було́ + genitive and не бу́де + genitive: учо́ра не було́ сві́тла, за́втра не бу́де дощу́. The absent thing — and even the absent person — sits in the genitive (мене́ не бу́де). This is the same genitive-of-negation pattern covered on the genitive of negation page.

Source-language comparison

For an English speaker, two reflexes must be unlearned. First, stop inserting "is/am/are" in the present — Він студе́нт is complete, and Він є студе́нт sounds stilted or wrong. Second, get used to the *predicate flipping case: in English "He was a student" keeps "student" identical to "He is a student," but Ukrainian changes студе́нт → студе́нтом the instant the verb surfaces. Train the pair "Він студе́нт / Він був студе́нтом" until the instrumental ending is automatic. Also note that Ukrainian negative existence is one word, нема́є (+ genitive), not "is not."

For a Russian speaker, the architecture is familiar — Russian also drops present "to be" and uses был/была and буду — but the forms are Ukrainian: був / була́ / було́ / були́ (not был/была), бу́ду / бу́деш / бу́дуть, and especially the existential є (Russian uses есть) and нема́є (Russian нет). One frequent slip: saying єсть on the Russian model — standard Ukrainian is simply *є. Keep the grammar, swap every form.

Common Mistakes

Key Takeaways

• Present: бути is omitted in predication (Він студе́нт); the invariant form є marks existence (є хліб), possession (У ме́не є…), and emphasis.
• Past: був / була́ / було́ / були́ (agrees in gender and number). Future: бу́ду / бу́деш / бу́де / бу́демо / бу́дете / бу́дуть.
• бу́ду & co. lead a double life: "will be" alone, and the future auxiliary before an imperfective infinitive (бу́ду чита́ти).
• The predicate noun is nominative in the present but instrumental in the past, future, infinitive and conditional: Він студе́нт → був студе́нтом → бу́де студе́нтом → хо́че бути студе́нтом.
• Imperative будь / бу́дьте; conditional був би / була́ б.
• Negative existence is нема́є + genitive (нема́є хлі́ба), with не було́ / не бу́де + genitive in past and future.