Britax Roundabout 40 Convertible Car Seat, Onyx

Britax Roundabout 40 Convertible Car Seat, Onyx

Travel safely with your child when you use this car seat that is designed with safety and comfort in mind.

Main features

  • Easy installation with built-in lock-off clips, Versa-Tether and Safe Guard LATCH Connectors
  • Tangle-free 5 point harness with 3 heights for convenience and a more secure fit
  • Equipped with Energy Absorbing EPS foam for additional protection during impact
  • Push button, one pull front harness adjustment
  • Rear facing: 5 to 35 pounds, forward facing: At least 1 year old and 20 to 40 pounds

Verified reviews


If you want a rear-facing seat for a long time go with the Marathon

I am a HUGE fan of Britax. I have had my 16 month old daughter in a Marathon since she was 10 months. I am very passionate about rear-facing to the max weight. I ordered the roundabout for a trip because I thought it would be a little easier to lug around the airport than my daughters Marathon. Also we are pregnant and I figured we could use this for baby #2. When I got the seat I instantly loved it. The Onyx color looks nice..the fabric feels nice and would clean up easily. Here’s the problem…my daughter is 16 months now and weighs only 22 pounds. This carseat sits rear-facing up to 35 pounds. She is only 25% for her height and she is at the max height for rear-facing in this seat. They can only sit rear-facing when there is 1 inch or more from the top of the seat to the top of their head. Sure, she can use it now, but obviously she would never make it to 35 pounds rear-facing. So basically this is a great seat, however, if you are concerned about having your child rear-facing as long as possible (which you should..type in rear-facing vs. forward facing on youtube and see the crash test results…if that doesnt convince you I dont know what will) this is not the seat for you. Go with the Marathon. My daughter has at least 4-5 inches left in her Marathon for rear-facing. Plus the marathon goes to 65 pounds forward-facing where the roundabout goes to 40. The roundabout is great for smaller cars so you have to do what you have to do. Just thought maybe this would help someone. I wish I had known this before. I returned the Roundabout to Amazon (which they are awesome with returns). I will lug her marathon on the trip and be ordering another marathon for baby #2.Good luck with your carseat choice. Whatever you get just make sure its installed properly. Take the time to take it to a certified station where they can check your carseat installation. Also the chest clip goes at the armpits..not lower. I swear..I have yet to see any of my friends put their kids in the seat right. Its not worth it to not do it right.

Jo Frazer, MT

Your child is safe with Britax

When shopping for a convertible car seat for my son, I decided that it was much more important to me to buy a seat that had very good review and high safety ratings. I splurged a bit (for my conservative budget) and bought the Britax Roundabout convertible car seat, and I have not been disappointed.I absolutely LOVE this car seat. It is built so well and is so sturdy. I feel so safe knowing that my son is in a Britax. The seat belts are great because they adjust and loosen very easily, so it is very easy to get my son in and out. I love the handy velcro on the seat belt which holds it out of the way when you put your child in. My mom bought a more inexpensive car seat for when she is watching my son, and while hers seems to work alright, I am always frustrated with the seat belt, which is VERY hard to tighten and loosen. The cheaper models I have seen are also a LOT more flimsy than the Britax.When shopping for a car seat, safety is most important! Do your research, and I think you will find, like I did, that Britax is definitely the way to go!

Yolanda Uncle Sam, LA

Awesome car seat!!!

I knew I wanted a well-rated, good looking car seat when I was doing research for ours, and wanted something different from the standard Graco and Fisher Prices out there. Britax consistently had great reviews and many awards so we decided to get the Roundabout. This model is more portable for travel since we travel a lot. We haven’t traveled overseas with it yet, but we really love it so far. I also have great peace of mind that I have a car seat that exceeds U.S. safety standards.

Jessica Washoe Valley, NV


I was a little concerned about this carseat AFTER I ordered it b/c of the reviews comparing this to the Marathon and Boulevard. Yes, it’s smaller…but I LOVE IT! It was easy to install, fits great rear-facing in my car (I have a volvo s-70), and my son seems to really by comfortable. I actually think the Marathon or Boulevard would have been to big for my car, with the carseat rear-facing. Yes, he will grow out of this faster than other Britax carseats…but by then I’ll probably want to buy a newer one anyway. This is a wonderful purchase, and I couldn’t be happier!!

Deanna Claridge, PA

Great Carseat

I purchased this to replace another recently purchased carseat. The previous one had been purchased in a hurry at a local store. It was a good brand name, so I thought all would be well. But it wasn’t! On the previous one, the crotch strap was much TOO close to the back of the chair, making it very difficult to fasten and causing me to utter explicatives each time I did so (in my head)!So, I went to Amazon to go back to Britax. In my main car, I have the Britax Shannon (because that is my daughter’s name). But since this car is not used very much, I wanted to spend less money if possible.I, of course, am VERY happy with this seat. As expected, the crotch strap is in the perfect spot. Everything is easy to do; installation, placing the baby (2 years) in the seat, and fastening her in. And it is very comfortable for her. And, most importantly, it is safe.I almost bought this for my daughter when her seat was damaged, but then went for the more expensive Shannon (don’t remember the model) since, after all, that is her name, and she was using it in the only car she drives….AND she often goes on long trips.

Josefa Rossburg, OH