Instrumental: Forms

The instrumental (narzędnik) is the case that answers kim? czym? — "with/by whom? with what?" — and the good news for learners is that its endings are among the most regular in the whole Polish system. There's essentially one masculine/neuter ending, one feminine ending, and one plural ending, with only a small handful of irregulars. The trap isn't the paradigm; it's a single vowel: the feminine instrumental -ą looks and sounds dangerously close to the accusative -ę, and swapping them flips the meaning of a sentence. Get the endings down and mind that nasal vowel, and the instrumental is one of the easier cases to control.

The singular endings

So masculine and neuter share -em, and feminine takes -ą. (Feminine nouns ending in a consonant, like noc "night" or rzecz "thing", take -ą spelled out as a regular ending: nocą, rzeczą — but those are a minority; the vast majority of feminine nouns end in -a and go to -ą.)

The velar softening: k/g → ki/gi before -em

Here's the one wrinkle in the masculine/neuter ending. Polish doesn't allow a hard k or g directly before the front vowel e. So when a stem ends in -k or -g, the ending isn't -em but -iem — written -kiem / -giem, with the i doing its softening job (it marks the consonant as soft, it isn't a separate syllable here).

The same softening shows up in -em after a few other stems, but k → ki and g → gi are the ones you'll meet daily (pociąg, rok, ranking, parking → pociągiem, rokiem, rankingiem, parkingiem). Note that the standard masculine -em otherwise attaches with no change: dom → domem, stół → stołem (with the regular ó → o alternation), nóż → nożem.

The plural ending: -ami (with a small -mi set)

The plural instrumental is gloriously uniform: -ami across all three genders. One ending to rule them all.

But there's a short, memorizable list of nouns that take -mi instead of -ami in the instrumental plural. These are old, very high-frequency words — you must simply learn them:

Note the consonant changes in the -mi set: ludzie → ludźmi, dzieci → dziećmi, liść → liśćmi (the stem consonant softens before -mi). These are irregular and worth banking as whole words — ludźmi and dziećmi in particular come up constantly.

Adjective endings

Adjectives agreeing with an instrumental noun take their own instrumental endings:

The -im / -imi variant appears after soft stems and after k/g (the same softening reflex): tani → tanim, drogi → drogim, wysoki → wysokim. So you get wysokim mężczyzną "(with) a tall man" and drogimi prezentami "(with) expensive gifts."

The big trap: instrumental -ą vs accusative -ę

This is the error English speakers make more than any other in the instrumental. For feminine nouns in -a, the instrumental singular is -ą and the accusative singular is -ę — two nasal vowels that differ only by which ogonek-bearing letter you choose. They are not interchangeable: the case, and so the meaning, flips entirely.

In the first, kobietę (-ę, accusative) is the woman I see — a direct object. In the second, kobietą (-ą, instrumental) is the woman I'm with. Same noun, one ogonek apart, opposite grammatical roles. The ogonek (ą vs ę) is not decoration here — it's carrying the case, and writing the wrong one is a real grammatical error, not a typo. Note too that tą (instrumental feminine of ta "this") pairs with kobietą, while the accusative would be tę kobietę.

Common Mistakes

Key Takeaways

• Singular endings: masculine -em, neuter -em, feminine -ą. After k/g the masculine/neuter ending is -kiem / -giem (pociągiem, dzieckiem, Bogiem).
• Plural is -ami for all genders, except the small irregular -mi set: ludźmi, dziećmi, końmi, gośćmi, liśćmi.
• Adjectives: -ym/-im (m/n sg), -ą (f sg), -ymi/-imi (pl).
• Never confuse feminine instrumental -ą ("with a woman", kobietą) with accusative -ę ("a woman" as object, kobietę) — the ogonek carries the case.