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UPPAbaby Knox Car Seat Review 2021 | Tadpole

Written by Anica Vujanic


Posted on March 27 2021

Last updated 7/23/21

What is the Knox Car Seat?

UPPAbaby just re-launched their first and only convertible car seat — the Knox. We're excited to be among the first to see and install this car seat for consumers and here are the main things you'll need to know about the Knox features and installation. The Knox is available for sale at Tadpole and we offer complimentary car seat fittings and installs to help you set up the car seat correctly in your vehicle. You can schedule a car seat appointment here.

Knox is a convertible car seat designed for babies weighing at least 14 pounds and up to the maximum of 65 pounds and 49 inches in height. UPPAbaby has pulled its original 2020 Knox car seat from sale voluntarily back in April of 2020 due to more lateral movement when in use in the rear-facing position. The new, improved 2021 Knox model has several added safety features to prevent this issue from happening. 

This Knox can be used in the rear facing mode from 14lbs and up to 45lbs and in the forward facing mode from 25 to 65 lbs, or until your child reaches 49 inches in height (there should be at least 1" of space between your child's head and top of the headrest). The American Academy of Pediatrics (AAP) encourages keeping your child rear-facing until they've reached the highest height or weight limit of the rear facing position for your particular car seat model. This recommendation is based on the fact that when you child is rear facing, the shell of the car seat will be the first thing to absorb the forces of the crash rather than your child's body thus limiting the potential of serious injury to the child.

The Knox has a five-point harness and an easy to adjust, no-rethread harness mechanism with eight positions for the headrest. The button on the top of the headrest allows you to adjust the shoulder harness straps easily by moving the headrest up as your child grows. There are four different Knox fashions and the price ranges from $349.99 and up to $399.99 (for Jordan – Merino Wool fashion).

Dimension wise, Knox is one of the heavier and taller car seats, weighing 32lbs and sitting at 28" tall but this car seat does provide a few extra safety features that we will discuss next.


Is the UPPAbaby Knox Safe?

There are a couple of innovative safety features built into and around the Knox base that make it a safe car seat from a child passenger safety perspective. Knox features an active support headrest that offers well-padded advanced side impact protection for the child's head and neck. There are two safety pods, one on each side of the base, meant to absorb the side-impact forces in case of a collision. UPPAbaby partnered with Koroyd®, an award-wining safety integrations company who uses welded tubes crumple technology to absorb maximum forces transferred to the child in a crash. Developed from aerospace safety research and now integrated into the KNOX base, Koroyd compresses and absorbs crash forces, which can further reduce the risk of potential injury to the child. Last but not least, Knox is one of the few convertible car seats in the US that features a multi-directional tether strap that can be used for rear facing installation. Typically, top tethers are only used for forward facing positions but UPPAbaby strongly recommends its use in the rear-facing mode since it helps reduce rotation and acts as an anti-rebound bar helping prevent the motion of the car seat towards the back of the vehicle in case of a crash. When used in the rear-facing mode, the tether is routed around the backside of the car seat (on the inside towards the middle of the car) and through the vehicle seat’s headrest and then hooked to the tether anchor usually found in the back of your car's trunk. Consult your vehicle's owner's manual to locate the exact position of tether hooks in your car.

multi directional top tether on a knox car seat

Is the UPPAbaby Knox Car Seat Comfortable?

The Knox features a two-piece Fit Inlay insert that is meant to improve the fit and comfort for children who are between 14 and 25 lbs. One cushion goes underneath the bum and one behind the child's back helping prop the child up into the correct seating position. Once the Fit Inlay cushion is removed at 25 lbs a smaller child could have a slight gap between their body and the single crotch buckle position. We don't think this is a safety concern per se, although too much space between the child and the crotch buckle could lead to slouching as the child settles in their seat. It's always good to check out the car seats in-person if you can, and we at Tadpole we'll be happy to help you test out different options and use our floor models to decide which car seats best fits your baby.

Knox's recline has four positions and the angles provide a good laid-back position for smaller infants and also a good "straight-up" seating position for older children in the forward facing mode. Headrest is well padded which cocoons the child's head nicely and might be more comfortable for snoozing infants. Jordan fashion features Merino wool covers which is the only fashion that is free of chemical flame-retardants.

Is the UPPAbaby Knox Easy To Install?

Tight installation in the rear facing position and with a vehicle seat belt is not very easy to achieve. Seat belt is the preferred installation method for the Knox due to the relatively low latch weight limits and this installation may seem intimidating at first because there are a few things going on inside the install base. Once you understand how to thread the lap belt portion of the lap/shoulder seat belt under the appropriate tensioning plate and then cinch the shoulder belt portion of the seat belt through the appropriate tensioning clip, you will feel a lot less intimidated. However, the tightening of the seat belt itself requires a significant amount of effort and pulling HARD to turn the visual SMARTSecure indicator fully green. This has to do with the angle from which the lap belt is pushing on the indicator from behind the plate so you might have little - or a lot of - trouble turning this indicator green depending on the seat angle in your car. The instructions manual states that the visual indicator can remain slightly red as long as you get a tight install at the belt path i.e. no more than 1" of lateral movement.

We found the rear facing seat belt installation more challenging than the forward facing because the Knox sits high up inside the car and you can't get behind it as you typically would in a rear-facing installation. This means that you can only work from the side of the seat which makes it harder to tighten the seat belt compared to the forward facing mode where you can push with your whole body, and even put a knee inside the seat, to help you compress the seat inside the vehicle seat crease and tighten the seat belt better.

install base and smart secure tension indicator on the knox convertible car seat

When rear-facing in the Knox, you can use any rear-facing recline position within the appropriate blue indicators on the side. The light blue zone is for kids under 25 lbs while the darker blue is for kids 25-45 lbs as labeled on the sides. One note is that in the 25-45 lbs angle range, the Knox sits pretty upright (similar to a forward-facing position almost) which in turn takes up little less front-to-back space in the car and the seat in front might not have to be pushed far forward. Once the child is over 45 lbs you must use the fully upright position for the forward facing installation. Overall, installing the seat does require a good look at the manual and potentially some extra time - and muscle - spent in the car trying to secure it tightly with a vehicle seat belt.

Is the Knox Easy to Use and Clean?

The Knox harness and headrest are pretty self-explanatory and easy to use and adjust. Cleaning of the covers is pretty straightforward as well. Button that activates the harness and headrest is visible and easy to push. The Fit Inlay is easy to remove and put back into place. The covers of the seat are completely removable by unzipping them on the sides and pretty straightforward to zip back up.

All Knox covers and inserts are machine-washable with cold water, on delicate cycle, and preferably in a front-loader machine. DO NOT BLEACH, PUT IN THE DRYER OR IRON. Always dry flat and away from direct sunlight before re-using the cushions.

What's the Warranty On The Knox?

UPPAbaby offers a 10-year limited warranty if you register your car seat within three months of purchase and with a valid receipt from an authorized retailer. We recommend that you always register your UPPAbaby car seats as soon as you can after purchasing it.

Knox car seat expires 10 years after the date of purchase so this makes it a lifetime warranty in this case. Please note every car seat is only good for one crash even if the crash is minor. If you suspect damage to your car seat and are not sure how to assess whether you need to replace it, please contact UPPAbaby's customer service directly by calling (844) 823-3132.

Please note the warranty is only valid in the original country of purchase. If you're buying your car seat in the Unites States and travelling/ moving outside the country you will not be covered by their warranty. UPPAbaby will not ship replacement or repair parts out of the country of purchase.

If you have any questions about the Knox, or any other car seat, feel free to give us a call or stop by. You can also schedule a one-on-one consultation with our certified techs who will be happy to help you with anything gear related.

This month, we were excited to welcome UPPAbaby new Hub Center to our neighborhood in the South End where their experts can also help you answer any car seat questions and help with the installation. You can book an appointment at their HUB here

Tadpole is located at 58 Clarendon Street, in the South End, Boston MA.

Written by Anica Vujanic, owner of Tadpole and active Certified Passenger Safety Technician.



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