In short

Polish expresses ability, wish, obligation and preference with a small set of modal verbs - móc (can), chcieć (to want), musieć (must), umieć (to know how to), woleć (to prefer) and powinien (should) - each conjugated for person and followed directly by an infinitive. The core rule is simple: conjugate the modal, and leave the second verb in the infinitive with no linking word. Only powinien breaks the mould - it agrees in gender and number like an adjective, not like an ordinary verb.

The rule

Polish has no separate grammatical class of modals like English “can / must / will”. Instead a handful of ordinary (mostly irregular) verbs carry modal meaning, and they all use the same frame: conjugated modal + bare infinitive. The infinitive never changes, whatever the subject.

• móc = can, to be able to, may: Mogę przyjść. (I can come.)
• chcieć = to want to: Chcę spać. (I want to sleep.)
• musieć = must, to have to: Muszę iść. (I have to go.)
• umieć = to know how to (a learned skill): Umiem pływać. (I can swim / I know how to swim.)
• woleć = to prefer: Wolę zostać. (I prefer to stay.)
• powinien = should, ought to: Powinienem odpocząć. (I should rest.)

móc vs umieć - two kinds of “can”

English “can” splits in Polish. móc is possibility or permission depending on circumstances (“I am able to / I may”); umieć is an acquired skill or know-how (“I know how to”).

• Nie mogę dzisiaj przyjść. (I can’t come today - circumstances.)
• Nie umiem gotować. (I can’t cook - I never learned the skill.)

For learned skills, and for what someone manages to do, you can also hear potrafić (to be able to, to manage), a close synonym of umieć: On potrafi rozpalić ognisko bez zapałek. (He can light a fire without matches.) Nie potrafię kłamać. (I can’t lie.)

Negation

Negation puts nie directly before the conjugated modal; the infinitive stays put: Nie muszę pracować. (I don’t have to work.) Note the meaning shift with musieć: nie musieć means “not have to / need not”, not “must not”. To say “must not”, use nie wolno (see Tips) or nie powinien.

powinien - the adjectival modal

powinien is special: it has no infinitive and no ordinary present tense. It behaves like a short adjective, agreeing with the subject in gender and number, and it takes the same mobile personal endings (-em, -eś, -śmy, -ście) you met in the past tense (Lesson 21). So a man says powinienem, a woman says powinnam, for “I should”.

Forms & patterns

Present tense of the modals that conjugate normally (watch the stem changes in móc, chcieć and musieć):

powinien - agrees in gender/number and carries mobile personal endings:

Impersonal modal expressions (one fixed form, then an infinitive):

Examples

Common mistakes

• Mogę do przyjść -> Mogę przyjść - no preposition or linking word before the infinitive after a modal.
• Muszę idę -> Muszę iść - the second verb stays an infinitive, never conjugated.
• Nie umiem przyjść dzisiaj -> Nie mogę przyjść dzisiaj - blocked by circumstances is móc, not umieć (a skill).
• Nie muszę palić (meaning “you must not smoke”) -> Nie wolno palić - nie musieć means “need not”, not “must not”.
• Ja powinien iść (said by a woman) -> Powinnam iść - powinien agrees in gender; a woman says powinnam.
• Powinnię pracować -> Powinienem pracować (m) / Powinnam pracować (f) - powinien takes mobile personal endings, not present-tense endings.
• Chcę że spać -> Chcę spać - one subject, so use the plain infinitive, not a że clause.

Tips

• One frame covers them all: conjugated modal + infinitive, with nothing in between.
• Two “cans”: móc = able by circumstance / allowed; umieć = know how to (a learned skill). If you could learn it in a class, it’s umieć.
• nie musieć = need not; to forbid, reach for nie wolno or nie powinien. Don’t let nie muszę drift into “must not”.
• powinien has no infinitive - you cannot say chcę powinien. Think of it as a short adjective: pick the gender (powinien / powinna / powinno) and add the personal ending (-em, -eś, -śmy…).
• The impersonal trio trzeba / można / nie wolno lets you state necessity, permission and prohibition without choosing a subject - perfect for signs and rules.
• woleć … niż / od: Wolę kawę niż herbatę or Wolę kawę od herbaty (I prefer coffee to tea).