Best Convertible Car Seats

Britax convertible car seats top others

Britax convertible car seats get the best scores in car seat reviews, though they represent the most expensive convertible car seats. The Britax Marathon (*Est. $280) , Decathlon (*Est. $295) and Boulevard (*Est. $300) are considered full-sized convertibles; Britax calls the Roundabout (*Est. $200) and the Diplomat (*Est. $250) "compact convertibles." All are similar, but differ in features, weight limit and upholstery. All have hand-washable seat padding and a five-point harness.

The least expensive Britax convertible car seat, the Britax Roundabout (*Est. $200) , has long been a favorite in car seat reviews, and in crash testing it performs extremely well. The Britax Roundabout may be tethered either front- or rear-facing; not all car seats can be used with a tether in the rear-facing position. The Roundabout also has a layer of EPS (the foam-type material in most helmets) to absorb shock during a collision and a five-point harness with up-front adjustment. In terms of negatives, the Roundabout is expensive, and some parents say that the Roundabout car seat is too bulky for their smaller vehicles.

A few parents posting to opinion websites say their taller-than-average children outgrew this seat relatively quickly. Overall, however, parents say the high price is worth it, and tests show the Roundabout to be a safe, comfortable car seat. The Roundabout can be used rear-facing for newborns up to 35 pounds. When in the front-facing position, the Roundabout is rated for a child that's up to 40 pounds and 40 inches tall. The seat itself weighs about 13 pounds.

Like the Britax Roundabout, the Britax Marathon (*Est. $280) is rated for babies up to 35 pounds in the rear-facing position, but when it faces forward, it can be used by kids until they weigh 65 pounds. This makes the seat larger and heavier than the Roundabout. Many parents with smaller vehicles complain that the car seat is simply too large for their cars, so if you have a new Honda Fit or Toyota Yaris, you might want to check out the compatibility database at CarSeatData.org (see our All Reviews section) and try the seat out in your own car before you commit. Most owners say their children are comfortable in the Marathon, but a few complain about overly tight crotch straps and insufficient recline. Overall, the Marathon is similar in features to the Roundabout. In one car seat review, the Marathon car seat scored a bit lower when used rear-facing with LATCH anchors, but it still passed crash testing safely.

The Britax Decathlon and Boulevard are evolutions of the Marathon, and both are rated up to 65 pounds in the front-facing position. The Britax Boulevard (*Est. $300) has some additional foam along the inner sides of the car seat for added head protection in a side-impact crash. The side-impact foam is height adjustable, so as your child grows, the side-impact padding can be adjusted. There's also an additional belly pad, and an inner infant liner so that babies fit more snugly in the seat. This extra padding is removable. The Boulevard car seat has up-front adjustments to tighten the harness, plus a new knob for adjusting the height of the shoulder straps without having to rethread them as your child grows.

The Britax Decathlon car seat (*Est. $295) costs about the same, and has similar features, including an infant pad, belly padding, side-impact protection foam and front harness adjustment. The side-impact foam adjusts height-wise. There are also three positions for the crotch belt, so it can be positioned closer to or further away from baby. For parents whose child is too short or young for a toddler seat, but has exceeded the weight limit of most other convertible car seats, the Britax Marathon, Decathlon and Boulevard are options.

The Britax Diplomat (*Est. $250) is the newest Britax convertible car seat. The Diplomat has the same height and weight limits as the Roundabout (rear-facing from 5 to 35 pounds and forward-facing to 40 pounds or 40 inches) and comes with side protection, a multi-position headrest, a no-thread harness and an infant body pillow. Like the Decathlon and the Roundabout, it has a push-button harness adjustment instead of a lever. Parents are generally happy with the Diplomat, but it doesn't get the same glowing reviews as the Boulevard or the Roundabout.

An alternative to the Britax car seats is the relatively new Sunshine Kids Radian65 (*Est. $200) . The Radian65 is getting some positive reviews, though it hasn't yet been tested by Consumer Reports. As the name suggests, the Radian65 is rated in the forward-facing position for children up to 65 pounds. The similar Sunshine Kids Radian80 (*Est. $280) can be used with the five-point harness for children weighing up to 80 pounds.

One feature that sets the Radian convertible car seats apart is that they are foldable. That makes them easier to transfer between vehicles or to bring along on airplanes or taxis. They are also narrower than other high-capacity convertibles since they have an inner structure made from steel alloy rather than plastic, making them a better fit in some cars. The downside? Despite its narrower profile, some parent reviewers say the Radian still isn't a good fit in their cars. Others complain that, at 22 pounds, it's too heavy to carry around even with the optional carry strap. Some parents find the crotch straps too restrictive for heavier children. Ease-of-use ratings aren't great according to the NHTSA, although most of the demerits involve poor labeling.

While the Sunshine Radian car seats don't work for everyone, they are filling a niche for heavy children who still need a five-point harness. We did read some comments from parents that the harness-strap height is the same for both Radian car seats -- so kids might outgrow the height of the Radian80 and be unable to take advantage of the higher weight limit. The Radian65 and Radian80 both have height limits of 53 inches.