Learn Finnish: Kuinka lyhyt uusi leikkaus on? - How short is the new haircut?

Both words mean "how", but when asking about the degree of an adjective (like "how short" or "how old"), kuinka is the standard choice in written and formal Finnish. Miten is typically used to ask about manner (in what way an action is done). However, in casual spoken Finnish, you will often hear people use miten for degree as well, so miten lyhyt would also be understood.

Doesn't leikkaus usually mean "surgery" or "operation"?

Yes, it often does! The word comes from the verb leikata (to cut). While it is heavily used for medical operations, in the context of hair or fashion, it simply means "a cut" or "haircut". It is a shorter, everyday way to say hiustenleikkaus.

The word order matches English exactly. Is that normal for questions with kuinka?

Yes, for this type of sentence! When you use kuinka with an adjective to ask "how [adjective]", that phrase (kuinka lyhyt) locks together at the beginning of the question. The subject (uusi leikkaus) and the verb (on) then follow, which feels very natural for English speakers.

Why are lyhyt, uusi, and leikkaus all in the basic nominative form?

This is fundamentally a simple descriptive "A is B" sentence, just turned into a question. In these sentences, the subject (uusi leikkaus) takes the basic nominative case, and the adjective describing it (lyhyt) must match it in the nominative case.