ds is tall and "heavy" about 40lbs and 41-42 inches. Â We ended up getting him a Britax Frontier, because it has 3 crotch strap positions instead of 2 (nautilus), but we bought it when he was still in diapers so he took up a lot of room! Â If you have a TRU or a BRU near you, you can try out the seats and see how well your lo fits.