California’s Car Booster Seat Law: What Parents Must Follow in 2025

California’s child passenger safety laws are evolving to protect young drivers. As of 2025, the state enforces strict booster seat requirements based on age, height, and weight—designed to maximize safety until a child can use a standard vehicle seat.

Why Booster Seats Matter in California

A booster seat isn’t just a legal formality—it’s a critical safety tool. According to the National Highway Traffic Safety Administration (NHTSA), children secured in booster seats are 45% less likely to sustain serious injuries in crashes compared to using seat belts alone if under 8 years old or shorter than 4’9”. California’s updated regulations reflect this science, placing clear responsibility on parents and caregivers to ensure compliance.

Current Booster Seat Requirements by Age and Size

Under California’s 2025 booster seat law, the rules are tiered based on a child’s development:

Infants and Toddlers (Birth to Age 2 or Under 4’9”)

Children must remain in a rear-facing booster seat until they reach the maximum height or weight limit of the car seat—typically around 4’9”. Rear-facing remains the safest option for infants and young toddlers, regardless of age, as it better supports the spine and absorbs crash forces.

Preschoolers and Young Children (Age 2 to Age 8 or 4’9”)

Once out of a rear-facing seat, children must use a forward-facing booster seat with a harness. California law requires this step when the child exceeds the rear-facing height/weight limit or turns 8, whichever comes first. This stage covers ages 2–8 or until standing height reaches 4’9”, whichever is later.

Transition to Seat Belts (Age 8 and Older or Over 4’9”)

Children over 8 years old or taller than 4’9” may use the vehicle’s seat belt, but only if properly fitted. The booster seat rule ends at this stage—California no longer mandates booster seats for older kids if they fit the vehicle seat safely.

Key Legal Requirements and Enforcement

California Vehicle Code §27315 explicitly states that all children under 8 must be secured in a properly used child restraint—either a rear or forward-facing booster seat. Law enforcement officers may stop vehicles to verify compliance. Fines for non-compliance start at $100 and increase for repeat offenses.

Police also conduct random checkpoints in high-traffic areas, especially near schools and parks. Officers use handheld sensors to detect improper use, so accurate installation and correct harness positioning are essential.

Common Mistakes Parents Make

• Using forward-facing seat belts too early: Seat belts don’t fit small bodies correctly and increase injury risk.
  
• Failing to secure height and weight limits: A booster seat meant for a 4’9