In this page, we will see the comparison between popular convertible car seats from Britax, namely, Britax Marathon, Boulevard, Allegiance, and Advocate.
Except for the Britax Allegiance, they all are convertible car seats that are equipped with the ClickTight installation system. They are all great car seats with very good safety ratings and user feedback but there are several key differences that set them apart.
We always recommend, to first make sure that the car seat will fit inside your car. Here is the size comparison of the Britax car seats.
|Length||Width||Height||Car Seat Weight|
|Britax Marathon ClickTight||23 inches||18.5 inches||23.5 inches||28.5 lbs|
|Britax Boulevard ClickTight||23 inches||18.5 inches||23.5 inches||29.4 lbs|
|Britax Advocate ClickTight||23 inches||20.5 inches||23.5 inches||30.6 lbs|
|Britax Allegiance||21 inches||18.5 inches||26 inches||19.5 lbs|
The Britax Marathon and the Britax Boulevard have exactly the same width, depth, and height (23″ L x 18.5″ W x 23.5″ H) while the Advocate is a little wider(23″ L x 20.5″ W x 23.5″ H). On the other hand, Britax Allegiance measures 21″ L x 18.5″ W x 26″ H.
Height and Weight Limits
The dimensions of the car seat are important but there is a more important thing to consider when choosing a car seat. It’s the height and weight limits of the car seat. This will decide how long your child can use the car seat before it is uncomfortable for her or not safe anymore. So you need to know how long the car seat will be able to accommodate your child.
|Rear-facing||Forward-facing||Child Seated Shoulder Height – Rear Facing||Child Seated Shoulder Height – Forward Facing||Child Standing Height Limit|
|Britax Marathon ClickTight||5-40 pounds||20-65 pounds||7.6 – 18.65 inches||12 – 18.65 inches||49 inches or less|
|Britax Boulevard ClickTight||5-40 pounds||20-65 pounds||7.6 – 18.65 inches||12 – 18.65 inches||49 inches or less|
|Britax Advocate ClickTight||5-40 pounds||20-65 pounds||7.6 – 18.65 inches||12 – 18.65 inches||49 inches or less|
|Britax Allegiance||5-40 pounds||20-65 pounds||9 – 16.75 inches||12 – 16.75 inches||49 inches or less|
Installation and Seat Features
Britax Marathon, Britax Boulevard, and Britax Advocate come with ClickTight installation system, which is truly easy to use.
The Britax Allegiance is also very easy to install using lower anchors that lock into place with a click and are released with the push of a button.
Below we also list other convenient features of each seat for easy comparison.
|ClickTight Installation System||Click & Safe Snug Harness Indicator||EZ-Buckle System|
|Britax Marathon ClickTight|
|Britax Boulevard ClickTight|
|Britax Advocate ClickTight|
|Britax Allegiance||Quick-adjust 10-position harness|
One of the primary differences between the Britax Marathon and the other Clicktight series car seats is the harness system. Britax Marathon does not have the Click & Safe Snug Indicator. The Britax Allegiance also have a different harness system.
|Layers of Side Impact Protection||SafeCell Impact Absorbing Base||SafeCell Impact Stabilizing Steel Frame||SafeCell Impact Absorbing Harness Pads|
|Britax Marathon ClickTight||1|
|Britax Boulevard ClickTight||2|
|Britax Advocate ClickTight||3|
Here one of the important things to look for is the layers of side impact protection. Every additional layer ensures additional protection, the Marathon and the Allegiance have one layer of side protection while the Boulevard comes with two layers and the Advocate comes with three layers of side impact protection.
Remember that, having more layers of protection is good but that doesn’t mean one layer is not enough, remember all the seats passed certain safety tests.
Britax Marathon ClickTight
Britax Boulevard ClickTight
Britax Advocate ClickTight
Britax Marathon ClickTight Color Options
Britax Boulevard ClickTight Color Options
Britax Advocate ClickTight Color Options
Britax Allegiance Color Options