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.

Plain-language summary — not legal advice. These provisions are displayed from the IIHS state law table (retrieved 2026-07-16). Laws change and have exceptions — verify against the table or your state's statute before relying on them. And the law is a minimum: NHTSA's guidance is to keep a child in each stage up to the seat's own height/weight limits, which usually lasts longer than the law requires.

Source: IIHS state law table · retrieved 2026-07-16 · MO

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.)
Fine (1st offense)	Up to $50; $10 for violations involving children taller than 4'9" or who weigh 80 pounds or more maximum base fine for a first offense; additional fees may apply.

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.

Seats at the stages Missouri names

The provisions above are written in ages, heights and weights. These are seats in our database at those stages, with the limits printed in each maker's manual. This is not a statement that any seat satisfies Missouri law. Check the seat's own limits and your vehicle's fit.

As an Amazon Associate we earn from qualifying purchases, at no extra cost to you. Affiliate links never affect our specs or which seats we compare.

Booster seats

Graco TurboBooster 2.0
- Booster (with back) 40–100 lb · 43–57 in · 4+ yrs
- Booster (backless) 40–100 lb · 43–57 in · 4+ yrs
Lightweight for travel
See price on Amazon
Chicco KidFit ClearTex Plus
- Booster (with back) 40–100 lb · 44–57 in · 4+ yrs
- Booster (backless) 40–110 lb · 44–57 in · 4+ yrs
Lightweight for travel
See price on Amazon
Clek Oobr
- Booster (with back) 40–100 lb · 43.3–57 in · 4+ yrs
- Booster (backless) 40–100 lb · 43.3–57 in
Narrow for 3-across
See price on Amazon
mifold Grab-and-Go
- Booster (backless) 40–100 lb · 40–59 in
Narrow for 3-across · lightweight for travel
See price on Amazon

All-in-one seats

Graco 4Ever DLX 4-in-1
- Rear-facing 4–40 lb
- Forward-facing harness 22–65 lb
- Booster (with back) 40–100 lb · 43–57 in · 4+ yrs
- Booster (backless) 40–120 lb · 43–57 in · 4+ yrs
Extended rear-facing · FAA-approved for aircraft
See price on Amazon
Britax One4Life ClickTight
- Rear-facing 5–50 lb · 18–49 in
- Forward-facing harness 30–65 lb · 35–49 in
- Booster (with back) 40–120 lb · 44–63 in
Extended rear-facing · FAA-approved for aircraft
See price on Amazon

Tap a seat name for its side-by-side page and the manual. Full lists: every booster seat · every all-in-one · narrow boosters for 3-across · 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.

What is the fine for a car seat violation in Missouri?
Up to $50; $10 for violations involving children taller than 4'9" or who weigh 80 pounds or more maximum base fine for a first offense; additional fees may apply. (As published in the IIHS state law table, retrieved 2026-09-24 — a summary, not legal advice.)

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.

Citing these specs? Go ahead — published manufacturer data, last verified 2026-06-11. Copy a ready-made reference:

All states: car seat laws by state · nearby in the list: Montana · Nebraska · Nevada · New Hampshire · New Jersey