Missouri car seat law (2026)
All children 3 years and younger, and all children less than 40 pounds, must ride in a child restraint; children 4 through 7 who weigh at least 40 but less than 80 pounds and are 4 feet 9 inches or shorter must be in a child restraint or booster; children 4 and older who weigh at least 80 pounds or are at least 4 feet 9 inches may use a booster or seat belt.
| Provision | What the IIHS table lists for Missouri |
|---|---|
| Child restraint | All children 3 years and younger, and all children less than 40 pounds, must ride in a child restraint; children 4 through 7 who weigh at least 40 but less than 80 pounds and are 4 feet 9 inches or shorter must be in a child restraint or booster; children 4 and older who weigh at least 80 pounds or are at least 4 feet 9 inches may use a booster or seat belt. |
| Adult seat belt | Ages 8 through 16 must use a seat belt; ages 4 and older may once at least 80 pounds or 4 feet 9 inches. |
| Rear seat | The law states no preference for the rear seat. (NHTSA still recommends all children under 13 ride in the back.) |
The law names ages — the seat's specs decide the switch
Every threshold above meets a spec question: is your child still within the seat's own height/weight limits for that mode? That's published manufacturer data, and it's what this site organizes:
- Keeping a toddler rear-facing longer → extended rear-facing seats (higher rear-facing limits).
- Moving from harness to booster → booster seats, incl. narrow boosters for 3-across.
- One seat across the whole journey → all-in-one (4-in-1) seats.
- Not sure a seat works in your car → how to check fit.
FAQ
What is the car seat law in Missouri?
All children 3 years and younger, and all children less than 40 pounds, must ride in a child restraint; children 4 through 7 who weigh at least 40 but less than 80 pounds and are 4 feet 9 inches or shorter must be in a child restraint or booster; children 4 and older who weigh at least 80 pounds or are at least 4 feet 9 inches may use a booster or seat belt. (As published in the IIHS state law table, retrieved 2026-07-16 — a summary, not legal advice.)
When can a child use just a seat belt in Missouri?
Ages 8 through 16 must use a seat belt; ages 4 and older may once at least 80 pounds or 4 feet 9 inches. Best practice is to keep using a booster until the adult belt fits properly — lap flat on the thighs, shoulder belt across the chest — regardless of the legal minimum.
Does Missouri require children to ride in the back seat?
Missouri law states no preference for the rear seat. That is the legal position, not the safety one: NHTSA recommends all children under 13 ride in the back seat, and a rear-facing seat must never go in front of an active passenger airbag.
Is the Missouri law the same as best practice?
No — the law is the legal minimum. NHTSA recommends keeping children in each stage (rear-facing, forward-facing harness, booster) up to the seat's own height and weight limits, which usually lasts longer than the law requires.
All states: car seat laws by state · nearby in the list: Montana · Nebraska · Nevada · New Hampshire · New Jersey