Booster Seats vs Car Seats With Harness Straps

Baby in car seat.
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Before you move your child from a car seat with a five-point harness to a booster seat, make sure they meet three important criteria. To sit safely in a booster seat, a child should be:

  • At least four years old (the older the better)
  • At least 40 pounds
  • Able to sit in the seat without slouching or squirming

There are many belt-positioning booster seats with minimum weight limits of 30 to 33 pounds, but the American Academy of Pediatrics has long recommended that children stay in a car safety seat with a harness as long as possible before transitioning to a booster seat.

There are many convertible seats and combination seats that allow you to use harness straps up until your child is 40 pounds or more (many can be used until kids are up to 65 pounds or 49 inches tall). These seats allow you to keep your child in a car seat with a harness for longer.

When to Switch to a Booster Seat

In general, the AAP states that "booster seats are for older children who have outgrown their forward-facing seats." But since they also state that children "should use a forward-facing seat with a harness for as long as possible, up to the highest weight or height allowed by their car safety seat manufacturer," they aren't encouraging an early switch to a booster seat. Instead, check the manual for your harness-style seat and use it until your child meets its weight or height limit.

The CDC recommends that children ride in a forward-facing car seat "until at least age five or when they reach the upper weight or height limit of their particular seat," after which they should be buckled into a belt-positioning booster seat in the back seat.

The National Highway Traffic Safety Administration agrees, stating that parents should keep kids in forward-facing seats with a harness and tether until they reach the top height or weight limit allowed the seat’s manufacturer. The NHTSA also offers an age range of four to seven years as a good time for when kids might be ready to move to a booster seat.

Why do they sell booster seats without harness straps with weight limits below 40 pounds if you should use a harness strap below this weight? Mainly because some taller kids outgrow their car seat even before they reach 40 pounds. So if your child's shoulders are above the top set of strap slots on your car seat, then you can move him to a belt-positioning booster seat.

Harness Car Seats for Bigger Kids

These car seats have higher weight and height limits (80 to 90 pounds and 52 to 58 inches). That means you can keep your child in them longer, which is helpful if your child is big for their age.

  • Britax Frontier
  • Britax Pinnacle
  • Graco Nautilus 80 Elite (80 pounds, 49 inches)
  • Maxi-Cosi Pria 85 and Pria 85 Max

Some kids complain about being in a car seat and want to be in a big kid booster. But they are safest in a car seat with a harness until they meet all of the age, height, weight, and maturity recommendations.

A Word From Verywell

The bottom line is that you shouldn't be in a rush to move your preschooler into a booster seat. To be safe, keep your child in a forward-facing car seat with a harness as long as you can. Always follow the manufacturer's instructions on height and weight limits, installation, and expiration.

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Article Sources
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  1. American Academy of Pediatrics. Child Passenger Safety. Published November 2018. doi:10.1542/peds.2018-2460

  2. American Academy of Pediatrics. Car Seats: Product Listing for 2019. Updated February 24, 2020.

  3. Centers for Disease Control. Child Passenger Safety. Updated September 25, 2019.

  4. U.S. Department of Transportation National Highway Traffic Safety Administration. Car Seats and Booster Seats.