Infant Seats

Many parents prefer using car seats made for infants for the first year or so of their baby's life. Parents can remove these seats from the car and carry the baby in the seat by the infant seat’s handle, and then put the infant seat back into the car, via the seat’s base that stays in the car. The appeal of infant car seats is that they are portable and designed as a ‘travel system,’ for the parent to remove the seat from the car and lock it into a stroller without taking the baby out. Most infant travel systems have weight limits of around 22 pounds, although some have higher weight limits. For big babies, this type of seat has a short shelf life, and often lasts less than a year.

Rear-Facing Convertibles

The American Academy of Pediatrics recommends that you keep babies in rear-facing seats until at least age 2 -- and beyond, if the seat meets the seat's height and weight restrictions. Since most babies outgrow their infant seats long before age 2, you might turn to a convertible seat, which you can use either rear or front facing. The height limits for rear-facing limits are lower than for front-facing seats on most convertible seats. Many children outgrow seats in the rear-facing position because of height restrictions rather than weight limits. Most convertible seats have weight limits of 30 to 40 pounds in their rear-facing position.

Front-Facing Seats

Most convertible seats have a weight limit of around 40 pounds when used in the front-facing position, but others will last a child until he weighs as much as 90 pounds. Some front-facing seats can double as booster seats when a parent uses a regular seat belt rather than the harness. Some of these front-facing seats have weight limits from 80 to 120 pounds, according to HealthyChildren.org, the official website published by the American Academy of Pediatrics. The weight limits of individual model can change from year to year, so do not rely on your knowledge of the weight limits on a previous seat model of the same name. Always read the manufacturer's instruction manual to determine the new seat's limits.

Boosters

Your child shouldn't use a booster until he reaches 40 pounds, the Car-Safety website reports. Boosters use the regular car seat belt rather than a five-point restraint harness and come in two styles, backless and seats with a back. The style with a back resembles a convertible car seat that's used in front-facing position. Many states mandate that children use boosters until they weigh at least 80 pounds and reach a height of 4 feet, 9 inches, according to HealthyChildren.org.