Booster/Seat Belt Height Question


New member
This is a question I have been thinking about, and I hope I make sense.

I have seen people here talking about outgrowing highback boosters by height, and wondering which booster has the highest belt guides. My question is if that is really important when using a booster.

Logically, it seems like the same rules should apply as they do for a 5point: you should not have harness straps below shoulders. But, some seatbelts in cars aren't necessarily above even an adult's shoulder. It's quite possible that when an adult sits in a seat their shoulder is above where the belt comes out. I'm especially thinking of seats where the belt comes out from the top of the seat.

Also, what if the added height of a booster makes the booster's belt guides higher than the seat belt? Doesn't that trump where the child's shoulders are within the booster?

I know this wouldn't be an issue in every car/situation, but it's just something I was thinking about.

Do you think adults are unsafe/at risk for spinal compression if the seatbelt is not at or above their shoulders? Should people who have adjustable height seat belts in their cars always adjust them to be at or above the shoulder?

If there have been crash tests with dummies with shoulders higher than seat belts, I'm thinking it might not matter so much where the booster belt guides are in relation to a child's shoulder. I'm not saying it would be my first choice though.

I thought I would pose this question to all of you experts and see what you thought, hope it makes sense. :)


Moderator - CPSTI Emeritus
Actually, those are good questions. :thumbsup:

At least one booster that I know of specifically states in the manual that it's outgrown once the shoulder is above the belt guide. So that alone is a pretty reason.

Also, they're not going to get much above the belt guide anyway because once their shoulder is above the belt guide, they're pretty close to having their ears over the headrest.

I think once they start growing over the top of the belt guide, it's not going to position it properly - the seat belt is going to start sliding down their shoulder.

As for having a belt guide over the seat belt retractor, that's been discussed before and I don't remember there being a definitive answer. My brain's a bit foggy though, so maybe there was?

Adults with adjustable shoulder belts in their seating position should adjust them so that the shoulder belt crosses their chest at the collarbone.


My mom's car has very low seat backs and with M's turbobooster in there the belt guide is above the retracter. It causes a very minimal twist/fold in the belt (instead of lying flat it looks like a sideways U) but nothing that has me especially worried. It certainly looks/is safer than when I tried her in the seat belt alone.
She's almost 9 btw.


oh, and my turbo manual says that the belt guides must be just above the top of the child's shoulders or the seat must be used backless.

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