Stage 3: Booster Seat

Is your child booster ready?

Ontario law states that a child must be in a harnessed seat until they weigh at least 18 kg (40 lbs). However, they may not be developmentally ready for a booster seat at that weight. This means sitting upright, even when sleeping, and not playing with the seat belt. Most children are ready for a booster by age five or six. Boosters in Canada are available for children up to 54 kg (120 lbs) and 160 cm (63”).

Most children will move from a harnessed seat to a high back booster. This provides belt guides for a better fit and head support while sleeping. Depending on the booster seat, a vehicle head restraint may also be required.

Backless boosters are for older children who do not need the belt guides or have excellent body control. Vehicle head restraints are required, with head support to at least the tops of the child’s ears.

For both high and low back boosters, both a lap and shoulder belt are required—never a lap belt only. The lap belt must be low and flat across the thighs, never on the belly. The shoulder belt should be flat across the collarbone, not against the neck or falling off the shoulder.

Booster Installation Check

  • The seat belt is positioned properly over the collarbone and flat across the upper thighs while your child is sitting in his/her booster. It does not cover the belly, dig into the neck, or slip off of the shoulder.

Child Seat Belt Check

  • Your child must be able to sit up straight all of the time to be safe. This means your child does not slouch forward or lean over when they fall asleep. 

Is My Child Ready for Stage 4?

Best practice is to keep your child in a booster until the seat belt fits well without it. This generally occurs once a child is 49” tall and around age 11. 

The ‘5-Step Test’ is an indicator that your child is ready for the belt-only. The test should be done in every seating position of each car, as it can be different.

  • Does the child sit all the way back in the vehicle seat?
  • Do the child’s knees bend easily at the edge of the vehicle seat?
  • Does the shoulder belt lay flat against the collarbone?
  • Does the lap belt sit low on the upper thighs?
  • Can the child remain seated for the whole trip, even while sleeping?