Tools · Car Seat
Missouri Car Seat & Booster Checker (2026)
Enter your child's age, height, and weight to see the minimum seat stage Missouri law requires and the first-offense fine (Up to $50). This is the legal minimum — not best safety practice.
Missouri car seat checker
4′9″ = 57 in. Enter only the boxes you have. Missouri uses the booster covers ages 4–7 who are 40–79 lb AND under 4′9″; reaching age 8, 80 lb, or 4′9″ (whichever comes first) exits it.
Missouri does not legislate rear-facing vs forward-facing by age; it requires a restraint appropriate per the manufacturer's instructions. Best practice from AAP (the pediatricians' association) and NHTSA (the federal highway-safety agency), not Missouri law: rear-facing to age 2+, then a harness, then a booster.
Heads up: A pending bill (HB 2170) would add a rear-facing requirement for children under 3. It is not law as of mid-2026; today the under-4 / under-40-lb rule sets no orientation. The under-8, 80-lb, 4′9″ booster rule described here is the current law.
- Child
- Not entered
- Minimum legal stage
- Enter age / height / weight
- Booster-exit rule
- the booster covers ages 4–7 who are 40–79 lb AND under 4′9″; reaching age 8, 80 lb, or 4′9″ (whichever comes first) exits it
- First-offense fine
- Up to $50
Plain-language summary, not legal advice.
This shows the minimum legal requirement in Missouri, not best safety practice, which is usually stricter, and not legal or safety advice. Always follow your car seat's manufacturer instructions. For the full four-stage rules, front-seat rule, and citation, see the Missouri car seat law reference, cited to Mo. Rev. Stat. §307.179 (last reviewed 2026-07-11).
How Missouri car seat law works
Missouri stacks three exit factors for the booster, and that is the detail most summaries flatten. A child needs a restraint or booster while all of these are true: at least 4 but younger than 8, weighing 40 to 79 lb, and under 4′9″. Reaching any one of the exits ends it: age 8, 80 lb, or 4′9″. Below age 4, or any child under 40 lb, the law requires an appropriate child restraint but says nothing about orientation, so rear-facing until 2 is best practice here, not law. Missouri also does not set a rear-seat age, so keeping younger children in the back is a recommendation. One timing note: a pending bill (HB 2170) would add a rear-facing rule for children under 3, but it is not law yet. The fine is an infraction of up to $50 plus court costs.
This checker shows the Missouri minimum legal requirement — not best safety practice, which is usually stricter — and is not legal or safety advice. For the full four-stage rules, front-seat rule, and citation, see the Missouri car seat law reference.
Car seat checkers for other states
Same tool, each with its own booster-exit rule.