In short

The conditional mood (умо́вний спо́сіб) is how Ukrainian says would: я хоті́в би “I would like”, ми пішли́ б “we would go”. You build it from a form you already know — the past tense — plus one small particle, би or б. There is no separate would-verb and no future/past split: one and the same form covers “I would go (now)” and “I would have gone (then)”. It carries two everyday jobs: imagining unreal situations (якби́ я знав… “if I knew…”) and softening a request into politeness (чи не могли́ б ви… “could you please…”).

The rule

• Formation = past tense + particle. Take the gender/number-marked past form (see Past tense (gender & number)) and add би/б: чита́в → чита́в би, чита́ла → чита́ла б, чита́ли → чита́ли б. The verb still agrees in gender (singular) and number, exactly as in the past.
• би after a consonant, б after a vowel. The choice depends on the sound before the particle, purely for euphony (compare the у/в, і/й rules): він хоті́в би (after -в… a consonant), вона́ хоті́ла б (after -а, a vowel). Both mean the same thing.
• The particle is mobile. It is a separate little word and usually leans on the first stressed word of the clause, not necessarily the verb: я б хоті́в, я хоті́в би, and хоті́в би я are all correct. In questions it often follows чи не: чи не могли́ б ви….
• No tense inside the mood. Ukrainian does not mark whether the wish is about the present or the past. Якби́ я мав час, я б відпочи́в can mean “If I had time (now), I would rest” or “If I had had time, I would have rested” — context decides.
• Unreal conditions use якби́ (not якщо́). For a real, likely condition use якщо́ + a normal tense (Якщо́ бу́де дощ, я лишу́ся вдо́ма). For an imagined, contrary-to-fact one use якби́ and put the conditional in both clauses: Якби́ було́ те́пло, ми пішли́ б на пляж. Note that якби́ already contains the particle (як + би), so you do not add a second one to it.
• Softening / politeness. With modal-type verbs (see Modal verbs) the particle turns a bald statement into a courteous one: хо́чу → хоті́в би “I’d like”, мо́жете → чи не могли́ б ви “could you”. This is the default polite register with ви (see ти/ви address (informal vs formal)).
• Wishes and impersonals. With no subject you get bare wishes: Хоті́лося б відпочи́ти “I’d love to rest”, Було́ б до́бре зустрі́тися “It would be nice to meet”.

Forms & patterns

Choosing the particle (same meaning either way):

Full paradigm — чита́ти “to read” (past-tense stem чита́- keeps a fixed stress):

Plural forms have no gender: чита́ли б serves ми, ви and вони́ alike.

Paradigm with a stress shift — могти́ “to be able” (watch the accent move off the root):

Conjunctions that already hold the particle:

Examples

Common mistakes

• я хотів бы -> я хоті́в би — Ukrainian has no letter ы; the particle is би/б only.
• вона хотів би -> вона́ хоті́ла б — the verb still agrees in gender; use the feminine past form.
• він хотіла б (mixing gender) -> він хоті́в би — masculine subject takes the masculine -в form.
• якщо́ я мав би час, я купи́в би… -> якби́ я мав час, я купи́в би… — an unreal condition takes якби́, not якщо́.
• якби я знав би -> якби́ я знав — якби́ already contains the particle; don’t double it inside the if-clause.
• вона хотіла би -> вона́ хоті́ла б — after the vowel -а you need б, not би.
• він хотів б -> він хоті́в би — after the consonant -в you need би, not б.
• Я думаю щоб (meaning “I would think”) -> я ду́мав би — щоб is the “so that” conjunction; the would form is past + би/б.

Tips

• Learn it as a two-piece recipe: past-tense form + би/б. If you can say the past tense, you can already say would.
• Pick the particle by ear: consonant before it → би, vowel before it → б. It never changes the meaning.
• Park б right after я/ти/ми/ви for smooth, natural speech: я б сказа́в, ми б залиши́лися.
• For politeness, keep хоті́в би / хоті́ла б and чи не могли́ б ви… ready — they are the everyday courteous phrasings with ви.
• Remember the spelling contrast: якби́ (if) and щоб (so that) are one word, but як би (how would) and що б (what would) are two.
• One conditional covers both time frames — don’t hunt for a separate “would have” form; let context show whether you mean now or back then.
• Both clauses of an unreal if-sentence go conditional: Якби́ … , … б … — mirror the particle in each half.