There are a lot of great milestones that should be exciting to celebrate! Some parents will be heard saying, “I can’t wait until my child…” and then finish that statement with any milestone like walking or talking.

This should not be the case with car seats though. Children should stay at each stage for as long as possible to keep them as safe as possible.

I heard a fellow car seat technician ask another parent, “Do you want the minimum for your child?”

Pause for a minute and realize the strength of that statement.

All parents want the best for their children, so using the best practice for car seats should be what parents choose for their children.

Laws vs. Best Practice

Most car seat laws that are in place have weight limits or ages for determining what is legal. But that is not always the safest.


Includes: Infant Only, Convertible & 3-Stage Car Seat

Best Practice: American Academy of Pediatrics strongly recommends that children remain rear-facing until they are 2 years of age or until they reach the maximum rear-facing weight or height of their car safety seat.

Law: under 9 kg (20 lbs)

It is time for the infant to come out of an infant only seat when the child is over the weight or height specified by the manufacturer OR the top of the child’s head is 2.5 cm (1 inch) or less below the top of the seat.

Outgrowing an infant seat does not mean that they should go forward facing. Since they should rear-face as long as possible, they will need another larger, rear-facing seat. Some rear-facing seat models can accommodate children up to 20 kg (45 lbs).

Rationale: Rear-facing child seats distribute the forces of a crash or sudden stop across the infant/child’s back and along the full length of the body. The forces are absorbed into the car safety seat. The infant/child’s head and neck are supported, therefore protecting the child’s head, neck and soft bones.


Includes: Convertible & 3-Stage Car Seat

Best Practice: Once a child has outgrown his/her rear-facing car safety seat, 30 kg (65 lbs)

Law: 9 kg to 18 kg (20 to 40 lbs)

The child has outgrown his/her forward-facing seat if:

  • The child is above the weight limit given in the manufacturer’s instructions.
  • The top of the child’s ears are above the back of the car safety seat or the harness comes from below the shoulders, then he must come out of that seat, regardless of his weight.

If the child is not yet 18 kg (40 lbs), he/she should go to a child/booster seat that can accommodate a taller child.

Note: Forward-facing car safety seats must be tethered.

Rationale: A 5-point harness seat allows the force of a collision to be spread out over the full skeletal frame of the child — their shoulders, chest bone and pelvis. It is safer for a child to use a 5 point harness as long as possible because their bones won’t be strong enough to handle using just a seatbelt until they are closer to 7 years of age.

Many new models allow a child to be harnessed up to 30 kg (65 lbs).

Booster Seat

Best Practice: Keep the child in a booster seat until she/he has reached the maximum height or weight of that booster seat.

At a minimum, Best Practice recommends that a child uses a booster seat until:

  • Child 9-10 years of age (for pelvic development)
  • Has a sitting height of 74 cm (29 inches) and is at least 1.45 m (4’9”) tall.
  • Can sit all the way back against the seat back with knees bent comfortably at the edge of the seat.
  • Lap belt rests across the upper thighs.
  • The shoulder belt is centered on the shoulder and chest.
  • Some booster seats have an upper weight limit of 54.4 kg (120 lbs)


  • Child under 8 years of age
  • Weighing between 18 kg to 36 kg (40 to 80 lbs)
  • Standing height of less than 145 cm (4’9”).

Rationale: A Booster seat…

  • Raises a child so the lap belt position is over the pelvis
  • Raises a child so the shoulder belt is over the shoulder
  • Prevents slouching

A child has outgrown the booster when she/he reaches the upper weight or when the top of their ears is above the back of the vehicle seat or high back booster. (Check the manufacturer’s instructions.)


Best Practice:

  • Closer to 9 years of age
  • Taller than 1.45 m (4’9”)
  • Passes the 5 Step Test:
    1. Is able to sit all the way back against the seat back with knees bent comfortably at the edge of the seat
    2. Lap belt rests across the upper thighs
    3. The shoulder belt is centered on the shoulder and chest
    4. Can stay that way for the entire trip without slouching or sliding forward

Law: A child can start using a seatbelt alone once any one of the following criteria is met:

  • The child turns 8 years old.
  • The child weighs 36 kg (80lbs)
  • The child is 145 cm (4’9”) tall

Rationale: A seatbelt is designed for an adult. A child at 8 years old is most likely too short to sit properly in the seatbelt. If the lap belt sits too high across the stomach, then there is more chance that the child will suffer from internal damage in a collision. If the shoulder belt sits on the neck, then the child risks damage to their neck. If it sits properly across the collarbone, then the stronger skeletal system will take the force of the impact instead of their neck. Or if the shoulder belt is slipping off the shoulder, the upper body will not be protected and the child will be thrown forward in a collision. If the child is able to slide forward and slouch, this increases the chance of the child sliding under the seatbelt during a collision, which increases the risk of strangulation by the shoulder belt.

Wendy is a Mom, wife and Certified Car Seat Technician (since 2008) who has a passion for child safety. You can read all about her adventures as a Mom of two at