Postage rates from USA to UK

[sneakerman]

Sorry if this has been posted already but I couldn't find a link.

I'm looking for standard postage rates from the USA to the UK for the following:

A3, A4 and A5. Standard would be 1 x photo of that size, SSAE and letter.

I've seen $1.05 to $1.75 but the dimensions vary from site to site.

Would it be correct say $1.05 for A5 and under and £1.75 for anything bigger?

Thanks in advance.