Britax Grow With You Booster Update

Back to the Booster SeatBritax Grow with Me Harness-2-Booster seat in mulberry sitting on sidewalk in sunshine

  • What: Britax Grow With You Booster Update
  • When: 5 to 10 years
  • Why: High safety rating, easy to install
  • Where: Amazon

Regular readers will recall I finally settled on a Britax Grow With You Booster for my daughter around this time last year. After trying several other options when she outgrew her Britax Marathon convertible car seat’s harness height, we committed to this booster version of Britax’s line of safety seats.

Brtiax Grow with You Harness2Booster seat next to Britax Marathon convertible car seat in third row of Mazda5
Our Britax Grow With You Harness2Booster seat originally installed next to a Britax Marathon convertible car seat in the third row of our Mazda5.

The Britax Grow With You offers two modes of use: a five point harness that goes up to 65 pounds, and a highback belt-positioning booster that goes up to 120 pounds. Unlike some models we’ve used, including the Graco Nautilus Elite 80 and Graco Turbobooster,  it does not convert to a backless booster.

I installed the Britax Grow With You in the third row of our 2021 Mazda Mazda5. Originally it rode next to a Britax Marathon installed forward facing in the same row. Then when my younger child upgraded, it sat next to a Graco Nautilus Elite 80. The seat itself overhung the bench car seat by a couple of inches, which is allowed when using the booster in harness mode.

Britax Grow with Me harness to highback booster combination car seat installed in back row of Mazda5
My daughter outgrew the one hand adjustable harness by height.

One year later, my daughter has outgrown the highest harness setting, which goes to 49 inches (and up to 65 pounds). Confoundingly, in belt-positioning mode, the booster seat cannot overhang the car’s bench seat, prompting us to either move the seat forward a row (and subsequently rearrange and reinstall at least one other car seat in the car), or switch it out.

We opted to switch it with the Diono Radian 3RX in our other vehicle. My daughter now uses the Britax Grow With You in our 2015 Audi Q7 installed on the passenger’s side in the second row. Thanks to the ClickTight installation (as well as the LATCH anchors not available in the third row of the Mazda), installation proved to be a breeze. 

Britax Grow With Me ClickTight mechanism on harness to booster seat
The ClickTight system on this Britax booster seat makes installation easy whether you use the seatbelt or LATCH system to install it.

It is, however, a larger seat, though the ability to use the LATCH system to secure the seat made a big difference for us. It meant that instead of using the seatbelt to install (because my daughter exceeded the LATCH weight limits), we could use the LATCH anchors. That gives us more flexibility to move the seat of the car when loading and unloading multiple passengers. The double cup holders also come in handy for drinks and snacks on longer drives. The harness stores inside the cover, so I don’t have to worry about losing it if we use the seat for another child and need to switch back to harness mode.

Britax Grow With You Harness2Booster two mode booster seat
In its new position in the second row of our SUV, the seat belt doesn’t retract freely when threaded through the belt guide path at the shoulder, especially with the headrest in lower positions.

On the downside, the seat belt doesn’t slip as easily through the belt guide with the headrest in lower positions. That often leaves slack in the seat belt even after my child buckles properly. I have to remember to check each time for proper seat belt usage since the seat belt can’t retract very well. 

Britax Grow With You Harness2Booster car seat installed in second row of Audi Q7 next to Diono Radian 3RXT
In the second row of our SUV, you can see that the Britax Grow With You booster takes up a lot more room than the Diono Radian 3RXT convertible car seat, which can also be used in booster mode (though it only has one height setting for the belt path).

Though I’m not thrilled about having to move the seat when switching to the belt-positioning booster mode, I am still very pleased with the ClickTight system and ease of installation with this seat. It offers a higher weight capacity for the five point harness, which I also found highly desirable. My petite daughter just moved into the belt-positioning booster at age eight and a half, when she outgrew the harness at 49 inches tall. (She weighed right around 50 pounds when we made the switch to booster mode from the five point harness.) Unlike the Diono Radian 3RX, I would buy this seat again, as I fully expect we will get several more years’ use out of the belt-positioning booster mode.

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