|Height is a variable. SOme kids grow in the torso, some kids grow in the legs. You have two kids the exact same height, one could fit perfectly in theseat and the other be too tall for it, because the second child has a long torso.|
I know most people get this, but I see this kind of thing on these threads all the time... like your child could easily outgrow the strap height limit at 38" standing height when the height limit for the seat is 52".
An interesting thing... I went 5ptbooster/harness shopping for ds2 yesterday. He is in a Britax Roundabout and is about 2 seconds away from outgrowing it - the shoulder straps are on their highest setting and are exactly at shoulder height but one tiny growth spurt and they'd be below. I was looking to get him the Graco Nautilus (5 pt. to 65 lbs. and belt positioning booster to 100 lbs.) -- took it down off the shelf and had him sit in it. The standing height limit is 27-52" I believe. My 3 year-old ~32.5 lb./38.5" son had MANY notches (placed around 2-2.5" apart) above where the shoulder straps fit him to move up to. Two other moms were there, one with an EXTREMELY tall and skinny 2 1/4 year old dd -- I mean, you'd look at this child and guess she was 4 years old and *maybe* weighs 28 lbs -- and she and my very average-sized ds needed the same place for the shoulder strap. Then a perhaps slightly small for age 5 year-old sat it in and needed only 1 notch up. But if you saw them side-by-side and only looked at height, the straps would go where you'd think they would, "long torsos" and all.