I have a skinny 9yr old and had to loosen the straps all the way for a very snug fit.

I have an extremely skinny 7 year old and it was too tight and very uncomfortable for him

I have a tall, skinny 9 year old

Runs small and barely fits my super skinny, tall 8 year old...

Doesn't fit my skinny 50lb 7 year old.

Wayyy too small for my very skinny 6 year old.