Stage 4: Seat Belt


What is a seat belt and how does it work? Older child passengers and all adult passengers ride facing the front of the vehicle in a lap/shoulder seat belt. Seat belts may also referred to as Stage 4.



Why do older children and adults use a seat belt? Seat belts are extremely important in reducing injuries and fatalities in crashes.

For children who are old enough, tall enough, and mature enough to no longer need a booster seat, the lap/shoulder belt safely fits on the strongest parts of the body. Correctly using a seat belt is the law everywhere in Canada, and vehicles come with lap/shoulder belts in nearly all seating positions.

Cars and seat belts are designed to best protect passengers in the most common and most frequently fatal types of crashes: frontal or front offset (front corner) crashes.

Best practice is to keep a child in a booster seat until they are tall enough to safely ride in just the adult seat belt. Most children are not tall enough to safely fit the adult seat belt until age 11 or 12. Height is most important for proper fit of the adult seat belt and kids may start to fit the adult seat belt around 4’9? (145 cm). Fewer than 5% of kids are this tall at 9 years old, the most common age listed in provincial laws.

Children should not ride in the front seat until age 13, and all passengers should choose lap/shoulder belts instead of lap-only belts when available. Everyone should buckle up for every ride.

Bare minimums to move out of a booster seat and to the adult seat belt alone depend on the province.



Who MUST use a seat belt? All adults, and older, taller children who safely fit the adult seat belt must use it for every ride.



Seat belts come in a variety of different types.

Lap/shoulder belts: The most common type of seat belt present in the majority of cars on the road today. This may also be called a 3-point belt. Sometimes lap/shoulder belts needs to be assembled before use, most commonly in middle seating positions of vehicles with fold-down seats. The upper portion is stored in the ceiling, and attaches to a mini-buckle located in the vehicle seat bight. Once assembled, it functions as a standard lap/shoulder belt.

Lap belt: Lap belts are no longer produced in rear-seating positions on new vehicles, but plenty of vehicles are still on the road with lap belts, most often in the middle. Lap belts are safer than no seat belt, but aren’t ideal for children or adults using just the seat belt. Lap belts are safe to install a car seat with.

Inflatable Seat Belts: Inflatable seat belts are found on Ford, Mercury, and some Mercedes models. They may be referred to as ISBs. Some car seats and boosters allow use with Ford brand ISBs. ISBs are an advanced safety feature that is described in vehicle manuals. They feel and look different from standard lap/shoulder belts but are worn the same way.


No really, how?

The adult seat belt relies on the passenger routing, securing, and adjusting the belt properly on every ride. The seat belt must fit correctly on the strongest parts of the passenger’s body.

How do you know if your child is ready to use the seat belt? How do you know if your child is ready to move out of the booster seat? Teach them the 5-Step Test.

5-Step Test

If the answer to any of the below is NO then they must continue to use a booster seat.

1. Does the child sit all the way back in the vehicle seat?

2. Do the child’s knees bend comfortably at the edge of the vehicle seat?

3. Does the shoulder belt lay across the collarbone and touching the chest, not riding up on the neck or slipping off the shoulder?

4. Does the lap belt sit low and flat across the tops of the thighs, not riding up onto the belly?

5. Can the child remain seated like that the whole trip, even when sleeping?

This 9 year old clearly does not Five Step (on left) but has excellent belt fit in a booster (on right).

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I have questions.

How do I get help to know if my child is ready to move out of their booster seat? How do I find out about seat belt fit?

Please ask us. Or ask another CPST near you. We tend to get to questions on our Facebook page more quickly than anywhere else, but if you don’t do social media please reach out via email to

We would be delighted to help you make choices to keep everyone safe in choose an appropriate seat that fits your family’s needs.


Stage 1: Rear facing
Stage 2: Forward facing
Stage 3: Booster seats
Stage 4: Seat belts