Now Sophia...she is the about the same length as London, maybe 1/2 inch bigger, only chubbier. She is around 3 lbs, can be up to 4lbs idk, i have not weighed her but she fits in it just fine too. So I'm guessing a 4 lber can fit in it if they are short
She can lay down in it and i can still close it and she is still comfortable.