I got these for my son when he was 2 and they fit perfectly but he does have a big head! My other son who is now 3 has a smaller head and I got him a pair of the other Aqua Sphere goggles - vista junior I think they are called and they fit him very well. Both are awesome goggle - well worth the money.

No, they are too big for my 4 yo

I think so, and they will last a while, my dainty 7yr old loves them.

They almost fit my 18 month old. If that helps?

My son is 2, going on 3 and they do fit him. At first though we did have some leaks over the nose bridge, but after a few goes of adjusting the goggles we don´t have the problem any more. If it is due to his face being small or the fact that he has a very flat nose bridge I am not sure of. But as I said, you just have to be a bit more precise when putting them on´and then it should be fine.

yes they are adjustable at the sides, very easy push button to expand or pull the side straps to tighten, my 2 year old has been wearing them for a few months and my 6 year old still wears his

I think in terms of strap adjustment they would.
Whether the google part will achieve a snug fit depends on the shape of your childs face. We got a pair for our daughter when she just turned 3 and they fitted well (they are quite flexible) although i'd say she has a bit of a 'moon face' - albeit a very beautiful moon!
Hope that helps.

I had the same problem with a pink mask. I think they had a batch of dodgy straps. If you stretch the strap do you see some holes? I contacted Aqua Sphere direct and they sent me a replacement strap.