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Britax advocate vs. Boulevard vs. Marathon – in-depth comparison

If you got the choice of car seats down to Advocate vs. Boulevard vs. Marathon from Britax, you’re well on your way

Still, you’ll need to do some thorough research to get there.

Here’s why…

Because the three Britax car seats are similar – the differences are so nuanced that they escape the naked eye. And therein lies the problem for a parent trying to choose between the three car seats.

Fret not; we have you covered.

Below is all the crucial information you need to make an informed decision.

This is what you’ll see:

  1. Britax at a glance – is it worth getting one of their seats in the first place?
  2. Clicktight installation system – what’s different about it and why you should care.
  3. What the three seats have in common
  4. Side by side comparisons of the Britax Advocate, Boulevard, and Marathon seats.
  5. If you’re still unsure – you’ll find the links to the full reviews towards the end.

Britax at a glance

You only need a glance at the top-rated seats from Britax to understand just how well-liked the UK brand is.

That comes as no surprise because there’s comfort in knowing your car seat is made by a company that initially made automotive safety equipment. And that was back in 1938.

Imagine the wealth of experience that goes into a Britax seat today.

Related reads: Britax vs. Chicco 

Britax Clicktight convertible car seats

When Britax came up with the ClickTight system, they obviously decided to make the most of it.

It’s featured in most of their better seats because the easy installation is paramount.

For you as a parent, getting a Clicktight seat means two things:

  1. The chances of installing your car seat wrong drop dramatically. That’s crucial because NHTSA research shows that 59% of car seats are installed incorrectly, often rendering their safety features useless.
  2. It makes your life easier because it’s easy to do.

Advocate or Boulevard or Marathon – similarities and differences

Let’s get to the meat of this guide by looking at the 11 main similarities.

  1. Safecell Impact Protection
  2. Clicktight convertible car seat installation system
  3. Safecell Impact absorbing bases – absorbs any energy on impact and reduces any forward movement in the instance of a crash.
  4. Safecell Complete Side Impact Protection – a feature of a Britax car seat designed to protect from debris in side-impact crashes
  5. Safecell Impact Absorbing Tether – comes with an innovative two-strap design – reduces forward movement and minimizes side to side movement of the child’s car seat in a collision.
  6. Safecell Impact Stabilizing Steel Frame – makes the car seat stronger, thus reducing forward flex and offering more strength to the car seat’s spine.
  7. Quick-Adjust 2 position buckle and harness – makes it easy to move the harness and adjust it to fit the needs of your growing baby.
  8. Safecell Impact Absorbing Harness ensures that the chest clip on the child safety seat is correctly positioned to absorb maximum energy of the impact in the instance of a crash.
  9. A typical Britax car seat comes with plush foam padding, removable pillow, shoulder pads, and buckle pads for ultimate comfort for the child.
  10. Most of the top seats come with a seven-position Recline with Automatic Level to ensure that your installation is as safe and comfortable as possible for your child.
  11. All the best car seats for airplane travel car seats are FAA-certified car seats.

Britax marathon vs. Advocate vs. Boulevard


Strap in because things will get more complicated before they get simpler. The only way to comprehensively compare is to drop them into a virtual dog pit.

Let’s do it…

Marathon is more budget-friendly

Most parents prefer the Britax USA Marathon Clicktight, probably because it comes at a better price than the Boulevard or the bulkier Advocate.

Britax Marathon ClickTight Convertible Car Seat, Verve

The Britax Marathon offers the least in terms of features, given that it lacks the ClickSafe function.

ClickSafe is a strap tightening mechanism that emits a slight click to inform you that the tight is installed at the proper tightness.

Nonetheless, the ClickSafe function is not that important as it has been known to provide false positives when the child is wearing bulky clothes or if the straps get caught on the seat.

Advocate is higher

If your child is atypically tall for their age, the Britax Boulevard vs. Marathon face-off will end with a clear winner – the Advocate, because it’s two inches higher.

The Britax Clicktight Boulevard is better than the Marathon in that it provides Secondary Side Impact Protection (SSIP)​.

Britax Advocate ClickTight Convertible Car Seat, Venti

However, the Marathon lacks the extra two inches of height. Its secondary side-impact protection is provided by the little pillow wings on the side.

Marathon vs. Boulevard vs. Advocate in side-impact protection

Compared to the Maraton, Britax Boulevard is a peg safer. Its side-impact protection can be easily adjusted with the lowering and adjusting of the shoulder straps for a more snug and robust fit.

As for the difference between the Britax Advocate Clicktight and the Boulevard, the Advocate adds a little bit more protection through the addition of side impact plastic on the car seat’s side to provide a third layer of protection in addition to the wings.

To sum it up – you have the Marathon on the “lower-end” in terms of side impact protection (one layer only); you have Marathon at two layers and the hefty Advocate at three layers.

I’m using the word lower-end only to compare the Britax seats to each other. In absolute terms, there’s nothing low-end about Marathon’s side protection.

An interesting tidbit about the pricing

Based on what we said above, you’d expect the Advocate to cost significantly more.

It doesn’t. At the time of completing this guide, the prices of the Boulevard and the Advocate are very close.

Britax Boulevard ClickTight Convertible Car Seat, Circa

With all other things equal, it’s fair to conclude that the Britax Boulevard vs. Advocate fight is won out by the former, at least in terms of the padding.

What it means for you

It means that, if comfort is a priority, Boulevard is the seat for you.

Again, we’re analyzing nuances here, and there’s little to no chance that your child would be able to tell the difference in comfort between Advocate and Boulevard.

Moreover, it might sound counter-intuitive, but comfort is not a top-tier factor in choosing a car seat, at least if you’re going with Britax.

Downsides of each Britax convertible car seat

But, if you’re willing to get nitpicky, the CONs of the seats might be the where answers are:

Downsides of the Marathon:

  • The padding leaves much to be desired (compared to the heft of Advocate and Boulevard).
  • It’s on the bulky side, especially when used in the rear-facing position.

Downsides of the Advocate:

  • No cup holder.
  • It’s the heaviest of the three (30.6).

Downsides of the Boulevard:

  • Big in rear-facing position (just like Marathon).
  • Heavy (not as heavy as the Advocate, but still weighty at 29.4).

Weight limits of a Britax car seat

As for the weight limitations, all the car seats come with the exact specifications as you can carry children in the forward-facing position from 20-65 pounds and in the rear-facing from between 5-40 pounds.

Related read: Britax car seat expiration

However, the layer of plastic gives the Advocate a bigger footprint, which would make the car seat a poor fit for small cars.

For travel with small cars, the Marathon and the Boulevard, which are small convertible car seats, are your best bet.

If you’re still unsure… Check out a full review of the Britax Marathon here and a full review of the Britax Advocate Clicktight here.​

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