help with my grammar please

[Shout]

If I want to write X would love to come to Louis's birthday.

Should it be as above or Louis' birthday?

both are correct.

some sticklers prefer Louis', but I like Louis's better because most people do actually say 2 distinct s sounds.

alternatively, you could just say "the party" ?

Louis'

Generally s's is used if two distinct s sounds are made.

If this Louis is pronounced Loo-ee, personally I wouldn't pronounce two s sounds, and would therefore write Louis'

But if this Louis is pronounced Lewis (one at my school is) then I would say "loo-iss-uz" and therefore write Louis's.

HTH

< English teacher. Both technically correct, but I prefer the Lois'