Grammar: How many does it costs?

Question

How many does it costs? or how many does it cost? Are they both correct? Thanks

Answer 1

Neither is grammatical.

A "cost" or "price" is uncountable, so the only acceptable form is

How much does it cost?

You could say "How many dollars/pounds/euros does it cost?" because those are countable quantities. But those are not usual unless there is some particular context, eg discussing different currencies. Note that even there, you use the singular "does", because the subject is "it", not the dollars etc.

Note also that does it costs is never grammatical, in any context that I can think of. The auxiliary do (does, did, doesn't, don't, didn't) is always followed by the base form of the main verb.