This bloomer runs big. It's a little difficult for them to stay on my daughters bum. She's 19 months old, 25 lbs (75th percentile weight, 85th percentile height), but she wears flat cloth diapers and sometimes only underwear. It's lovely and warm, it will prevent chafed knees in case of a fall outside, plus it's so lovely that she can go off any slide in the rainy winter season here and actually slide off! Also, it will keep her warm despite the wool being slightly damp. I like the overalls better, even though I appreciate the ease of pulling these down in case she needs to use the potty, but the boiled wool overalls stay on her better. Runs big, I think she'll get another season out of these!