Car Seat Safety: When to Move to a Booster


switching to a booster seat

Not ready for the booster yet!

Photo by Annies_mommy

"My daughter is 33 pounds and 36 inches and will be 2 next week. She is getting tall for her seat and there isn't much more of the belt I can let out to fit her shoulders. Would a high-back booster seat that is for 30-80 pounds be okay?"

"My daughter just turned 4 and she is small for her age. She is normal height but only weighs about 29 pounds. I was wondering about moving her to a booster seat ... maybe one with a harness?"

"My 2 year old daughter weighs about 35 pounds and is around 35 inches tall. The booster seat box says that she has to be 35 pounds and 37 inches. I am a little scared to put her in it. When did you switch your toddler from a 5-point harness to a booster seat?"


It's one of the most commonly asked car seat questions on CafeMom. So here's CarSeatJunkie, a CafeMom to a 3 and 6 year old, certified child passenger seat technician, and administrator of the Car Seat Safety group, to set us straight on the famous 4 years and 40 pound rule for when it's safe to move toddlers to the next travel stage:

CafeCynthia: Could you explain the 4 years and 40 pound rule?

CarSeatJunkie: The rule means that a child should be 4 years old AND 40 pounds before moving from a 5 point harness to a belt-positioning booster seat. So, the child should meet BOTH criteria, not one or the other. But there are exceptions -- see below.

Where did the rule come from, anway?

It's not a federal or state law -- as technicians, we recommend it because there needs to be a certain amount of maturity that comes with sitting properly in a booster seat. The 40 pound thing is the "general" weight limit on most commonly used car seats, and that's the age when most kids would be transitioned to a booster. (Some do have higher weight limits, in which case it's much safer to leave your older toddler in the 5-point harness.) But there are always exceptions.

Can you give me an example?

Say a 2 year old is 40 pounds. I always tell the parent that I would recommend a higher harnessing (5-point) weight seat -- one that will go up to 65 or even 80 pounds.

Having two children myself, I found that neither one were mature enough to sit in the correct position in the booster.

What is that "correct" position?

The child needs to sit with their bottom and back all the way back in the booster with the seat belt lying across their shoulder/chest properly and the lap portion across their upper lap/hip bones. They need to be able to stay in this positon for the entire ride.

You also need to read the suggestions on the individual booster seat you are considering for your toddler. For example, the Graco TurboBooster with the highback is designed for children ages 3 to 10 and 30 to 100 pounds, so putting a 2 year old child in that seat -- even if they weigh 30 pounds -- goes against those guidelines.

In addition, the seat belt should lie as flat and as close to your child's body as possible to eliminate any slack so your child won't move forward as much during a crash. Twisted belts not allowed!

If my child is 4, 40 pounds, and mature enough to sit properly in a booster, can I skip the high-back booster and go right to the backless?

Researchers have not found a big difference between the two in crash tests. However, if your toddler consistently falls asleep, a high-back booster will help keep him in the proper position, rather than leaning on the door panel or falling completely out of the seat belt. A high back also offers side impact protection.

These are just guidelines, ladies. You need to pull out your car and child seat manuals for the proper weight limits and instructions for installing and using your seat. And, if you can, ask a certified car seat technician to check your work.

++Is your toddler in a belt-fastening booster seat? Did you follow the 4 year AND 40 pound rule?

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