Whose is that's?

A question for native speakers. Do you say

'Whose is that?' or 'Whose is that's?'

I know the second one sounds better to me, the first one sounds incomplete somehow, although I think it is the standard English form.

Why does the second one sound better? It's indeed nonstandard, and I don't think I've ever heard it... moreover, I can't think of a logical reason to make "that" possessive, either, because the item in question is *being* possessed, rather than possessing something else. Only things that possess other things can take the possessive.

It also might help to consider the way such a question would be answered.

Q: Whose is that?
A: That is John's -- not *That's is John's.

It's the same grammar except that the question has inverted word order because it's a question.

- Kef

<<'Whose is that?' or 'Whose is that's?'>>

I'd also vote for "Whose is that?"

Sorry, I guess that sounded like I was a non-native speaker asking native speakers what they say. I'm a native BrE speaker, and I know I say it, so I must have heard it, but it did one day strike me as odd. You are right, there's no reason grammatically, in fact it should be very wrong. I know it certainly isn't a general BrE thing, maybe it's a dialect thing though.

It's not as bad as something else that is said where I grew up though. I often say, for example: I don't know as I should' instead of 'I don't know that/whether/if...'. I only realised this wasn't usual when a huge confusion arose during an email conversation with a friend. We were planning to go to the cinema and were discussing which film to see. I wanted to see one, but not the other, so I wrote:

'I don't know as I really want to see Film A, but Film B looks good'. My friend replied:

'OK let's see Film A then'

I then replied something like 'NO, I said I didn't want to see it'. He insisted that I had said the opposite and told me to go back and reread it, which I did and and replied once again that he was wrong. Only when I read it again did I see what had happened. There is the issue of it really requiring a comment after the 'don't know', but still I think a lot of people would misunderstand. I know if I had actually said it, my meaning would have been obvious from the intonation, but still I find it amusing that in written form he actually understood the complete opposite of what I wanted to say.

I still say it, it's so ingrained. I think I would now catch myself in writing now though and write it a way which makes sense lol

"I don't know as I really want to see Film A, but Film B looks good."

I would interpret that as: "I don't know, because I really want to see Film A, but Film B looks good."