Except vs. Except For

They were all tired except John.

Except and except for

After words like all, every, no, everything, anybody, nowhere, whole etc., except and except for can both be used with the same meaning.

• He ate everything on his plate except (for) the beans.

In other cases we usually use except for.

• That was a good essay except for a few spelling mistakes. (NOT — except a few spelling mistakes.)
• Nobody came except (for) Peter and Alice.

We use except, not except for, before prepositions and conjunctions.

• He is good-looking except when he smiles. (NOT — except for when he smiles.)

Note that we use object pronouns after except (for).

• Everybody came except him. (NOT — except he.)

Except + verb

A verb form after except usually depends on what came before. Infinitives are normally used without to.

• He does nothing except sleep all day. (does — sleep)
• She is not interested in anything except cooking. (interested in — cooking)