when can you stop using car booster in michigan

[GiaMarie]

In Michigan, a child can stop using a car booster seat when they are 8 years old or 4 feet 9 inches tall, whichever comes first. However, simply meeting the legal minimum isn't always the safest option. The most reliable indicator is the 5-Step Seat Belt Fit Test, which ensures the vehicle's adult seat belt provides proper protection without posing a risk of injury.

The law (Michigan’s Child Passenger Safety Act) is specific: children must be in a booster seat until they reach age 8 or a height of 4'9". Even after that, they must ride in the rear seat until they are 13 years old. The goal is to position the seat belt correctly on a child's body. An ill-fitting lap belt can ride up over the stomach, and a shoulder belt can cut across the neck, both of which are dangerous in a crash.

You should perform the Seat Belt Fit Test with the child sitting upright against the vehicle seat back:

1. Knees bend at the seat's edge: Their knees should bend comfortably at the edge of the seat.
2. Lap belt on hips/thighs: The lap belt must lie snugly across the upper thighs, not the soft abdomen.
3. Shoulder belt on chest/shoulder: The shoulder belt should cross the center of the chest and rest on the shoulder, not the neck or face.
4. Child can stay seated: The child must be able to maintain this position for the entire trip without slouching.

If the child fails any part of this test, they should continue using a booster seat. Many children need a booster until they are 10 to 12 years old. Safety, not just legality, should be your primary guide.

Key Milestone for Booster Seat Transition	Michigan Legal Requirement	Recommended Safety Best Practice
Minimum Age	8 years old	Use the 5-Step Test; age is just one factor.
Minimum Height	4 feet 9 inches (57 inches)	Child must pass the 5-Step Test.
Seat Position	Law does not specify.	Ride in the back seat until at least age 13.
Lap Belt Fit	Not specified by law.	Must lie low on the hips, touching the thighs.
Shoulder Belt Fit	Not specified by law.	Must cross the shoulder and chest, not the neck.

[Paige]

We just went through this with my nephew. The rule is 8 years old or 4'9", but that's just the bare minimum. The real trick is the seat belt test. Have your kid sit back, buckle up, and check where the belt lies. If it's cutting across his neck or the lap part is on his belly, he's not ready. He might be tall for his age, but his bones are still developing. We kept our guy in a booster until he was almost 11 because he kept slouching. It’s about safety, not just a birthday.

[LeAbel]

As an engineer, I look at the data. The law provides a clear threshold: age 8 or 57 inches in height. However, the biomechanics are what matter. A booster seat's primary function is to position the seat belt correctly over the stronger skeletal structures—the pelvis and clavicle. An improperly positioned belt transfers crash forces to the softer abdominal area and neck, increasing the risk of severe internal injuries. Always use the 5-step fit test. The legal age is a guideline; proper physical fit is the requirement.