Adequate height and weight limits. Basic infant car seats will have at least 22-pound, 29-inch weight and height limits, but a higher-capacity seat might be worth the investment if you want to wait as long as possible to switch to a convertible car seat. Basic convertible car seats will have at least 40-pound, 40-inch weight and height limits forward-facing, but a seat with higher limits might be worth the investment since most kids aren't ready for a booster until 5 at the youngest, according to CarSeatsForTheLittles.org.
LATCH system for easy installation. LATCH, or Lower Anchors and Tethers for Children, is intended to streamline car seat installation; push-button or rigid connectors will be easier to use than older hook-style LATCH connectors.
Adjustable harness heights. All infant and convertible seats should have a five-point harness with several slots that can accommodate a growing child, but a seat with a no-rethread harness that is adjustable from the front will be easiest to use.
An adjustable recline. In infant seats, bases with an adjustable recline will help parents install the car seat at the proper angle without resorting to bolsters such as rolled towels or pool noodles. Some rear-facing convertibles must be reclined at an angle specified by the seat's manual, while others allow any angle within a specific range; manufacturers may also include multiple recline settings for forward-facing children, too.
A reasonable return policy. Certain car seats simply might not fit well in certain vehicles -- check your store or manufacturer's return policy before you buy.
Will the car seat be for everyday or occasional use? A less expensive infant or convertible car seat with thinner padding might be perfectly fine for a grandparent's car or sparsely used second vehicle -- all car seats on the U.S. market must pass the same federal safety tests. But if you know the seat will receive heavy use, you may want a comfier seat with more side-impact protection. If you'll have to move the seat from car to car, look for one that is lightweight and easy to install.
Is space tight in your vehicle? You may have a smaller vehicle with a cramped back seat, or perhaps you need to fit three car seats in one row. Look for a narrow car seat to maximize space -- some infant seats are as slim as 15 to 16 inches across. A narrow convertible seat will be 17 inches or less across. Also consider that car seats with taller shells can hog front-to-back space, so be sure the person sitting in front of the installed car seat still has enough legroom. Car Seats For The Littles compares several infant seats in a compact car, while CarSeatBlog.com compares popular convertibles.
Do you want to use the seat for more than one child? All car seats expire. But manufacturers are rolling out seats with higher height and weight limits, meaning your child might be in the seat longer. This makes it especially crucial to know the expiration date if you hope to use it again, especially several years down the road. Many models expire six years after they're manufactured, but a few have longer shelf lives -- check before you buy.
Is the seat fabric easy to remove and clean? Infant car seats are subject to spit-up and diaper blowouts, while convertible car seats may absorb spilled juice and potty-training accidents. Despite this, a surprising number have covers that are hand-wash or spot-clean only. Machine-washable fabric will make your life easier. Note that car-seat straps should never be submerged in water or anything else -- it can weaken them and remove fire retardants.
Do you want to use your infant car seat with a stroller system? Some common models such as the Graco SnugRide are compatible with several types of strollers and stroller frames. Others may be limited to strollers made by their manufacturers. Also make sure the seat's canopy offers adequate sun protection if you'll be out strolling on sunny days.
Will you carry the infant seat a lot? If you don't want to disturb your snoozing baby, chances are you'll be toting around your car seat. Many seats weigh roughly 9 to 10 pounds -- baby not included -- but some are as lightweight as 7 pounds and others as heavy as 13 pounds. Also be sure the handle is comfortable to grip. Some manufacturers offer triangular or zigzag handles for easy carrying, while others offer a straight handle with ergonomic padding. Test what feels best before you buy.
Do you want to use a convertible seat from birth? With a few exceptions, most convertible car seats will accommodate babies from birth. Be sure to check minimum weight limits, harness tightness, and whether the seat comes with adequate padding to support a small infant, advises Car Seats For The Littles. If you decide to use a convertible right away, you won't have the convenience of being able to detach the seat from a base that stays in the car, as with infant car seats.
How long do you plan to keep your child rear-facing in their convertible seat? Infant seats are simple in this regard -- you must always use them rear-facing. However, convertible seats can be rear- or forward-facing. Laws vary from state to state, but the American Academy of Pediatrics recommends keeping children rear-facing until age 2 or they outgrow the rear-facing limits of their seats. While most convertible car seats can accommodate smaller children rear-facing until or beyond 2, parents may have to flip taller or heavier children forward-facing sooner than they would like. Unfortunately, looking at a seat's rear-facing weight and height limits may not tell you the whole story. Many manufacturers require you to turn your child when their head is an inch from the top of the seat's shell, which may be at a height below the stated rear-facing limit. Car Seat Blog recommends several convertible car seats that are most likely to get tall and heavy children rear-facing beyond the age of 2.