Aside from the easy installation and no-rethread harness, the Britax Marathon Clicktight underperforms when compared side by side with the Diono Radian 3RXT. In what aspects? Read on.

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ideal use


Diono Radian 3RXT
Britax Marathon Clicktight
Rear-Facing Weight:
5 to 45 pounds
5 to 40 pounds
Rear-Facing Height Limit:
Up to 44 inches
the head should be 1 inch below the top of the headrest
Forward-Facing Weight:
20 to 65 pounds
20 to 65 pounds
Forward-Facing Height Limit:
Up to 57 inches
Up to 49 inches
Booster Weight Requirement:
50 pounds
Booster Weight Limit:
Up to 120 pounds

Being an all-in-one car seat, the Diono 3RXT has the most weight and height capacity that you can maximize. Parents choose to ignore the downsides of the 3RXT because it can sit children rear-facing for as long as possible.

Not many convertible car seats can have a child seated rear-facing this long.

will it fit in my car?


Diono Radian 3RXT
Britax Marathon Clicktight
16.5 inches
18.5 inches
28.5 inches
23.5 inches
16 inches
23 inches

The narrow profile is one of the selling points of the 3RXT. Parents who have triplets or those who need three of it in a row can make it possible with the Diono 3RXT.



Diono Radian 3RXT
Britax Marathon Clicktight
Do I need to use a pool noodle/rolled towel?
Easy To Install Rear-Facing?
Easy To Install Forward-Facing?
Easy To Uninstall?

Installing the 3RXT is not the easiest, but if you watch the videos in my separate review of the 3RXT, it can be done with some techniques.

Installing the Marathon Clicktight is regarded to be easier to do.



Diono Radian 3RXT
Britax Marathon Clicktight
Country Of Origin:
Steel Frame:
Five-Point Harness?
Side Impact Tested:
Approved For Airplane Use:
Easy To Buckle And Unbuckle?
Britax Marathon ClickTight Convertible Car Seat | 1 Layer Impact Protection - Rear & Forward Facing - 5 to 65 Pounds, Verve
Price: $299.99
(As of: 2020/10/13 3:26 pm - Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on at the time of purchase will apply to the purchase of this product.
2 new from $299.991 used from $215.79
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the seat


Radian 3RXT
Marathon Clicktight
Is The Material Breathable?
Seat Weight:
28.1 pounds
28.5 pounds
Machine Washable Cover?
No-Rethread Harness?
Comes With An Infant Body Support?
Just removable pillow
Easy To Remove Cover?
8 years/10 years
10 years
Comes With A Cup Holder?
Shoulder Harness Has Pads?
Leg Straps Has Pads?

Both seats are a beast to carry. They are built like a tank so carrying them with you to the airport will need a car seat travel cart.*

You can only hand-wash the Britax Marathon Clicktight seat cover.

The Britax Marathon Clicktight’s seat harness is very convenient to adjust. Moving the headrest up and down will make the harness height adjust with it too. That’s something you can’t do with the 3RXT.

If you are particular with the cup holder, make sure to get the Marathon Clicktight from a seller who includes a cup holder with the purchase. As per default, the Marathon Clicktight is sold without it.


There is approximately USD 40 price difference between the Diono Radian 3RXT and the Britax Marathon Clicktight.

The Britax Marathon Clicktight is more expensive. Let’s see why is that so.

  1. The Britax Marathon Clicktight is easier to install both in the rear-facing and forward-facing mode.
  2. It’s convenient to adjust the harness height as your child grows because of the no-rethread harness.

Are the above points worth the extra USD40? I think yes.

However, the Diono Radian 3RXT has a lot of good points that the Britax Marathon Clicktight cannot give.

  1. The Diono Radian 3RXT has a higher rear-facing weight limit.
  2. It has a higher forward-facing height limit.
  3. It can be used as a booster until 120 pounds.
  4. Its 44 inches rear-facing height limit is the main reason why parents are getting the 3RXT. It’s not usually found in most convertible car seats.
  5. Its width is narrow enough to fit three of it in a row.
  6. You can use an angle adjuster* to elevate the seat to give more legroom to the passenger directly opposite it.
  7. You can fold it to “easily” bring it with you on the plane.
  8. It has a machine washable cover.
  9. It comes with an infant body support.
  10. It is guaranteed to come with a cup holder.

Despite the cheaper price, the Diono Radian 3RXT has the above 10 advantages over the Britax Marathon Clicktight.

Between the two, I’d choose the Diono Radian 3RXT.*


Do You Need More Help To Decide Between

The Diono Radian 3RXT Vs Britax Marathon Clicktight?


Check Out My Review Of The Diono Radian 3RXT Convertible Car Seat

Read My Britax Marathon Clicktight Review


What Do You Think?

I’d love to know your thoughts in the comments section below!




The Diono Radian 3RXT
I'd love to know your thoughts in the comments section below!

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  1. I have a Diono RXT for both of my sons. We LOVE these seats! But the best part is never having to worry if the seats are safe enough – with a full steel frame (Britax only has a partial steel frame), I know my babies are in the safest seat. And I love that my these seats last from birth all the way to 10 years of age! I highly recommend a Diono!

    1. Hi Kristina,

      Thank you for sharing your thoughts and experience with the Diono Radian RXT. I am sure my readers will find it useful and helpful for making a decision. 🙂


  2. Can you recommend a car seat that is suitable for both newborns and toddlers? I love the Diono because of the head support, but the Britax for the size.

    1. Hi there,

      There are a few All-In-One (newborn to booster) car seats that I have reviewed. But most parents who got them would advise waiting until your child is old enough to have proper head and neck control as they can be too upright for a newborn.

      Even the two-way (newborn to forward-facing pre-schooler) car seats that I have reviewed seldom achieve the “perfect fit” for newborns.

      There are few car seats that stood out though.

      1. Graco 4ever (My Review Here)
      2. Evenflo Symphony DLX (My Review Here)
      3. Safety 1st Go and Grow (My Review Here)
      4. Diono Radian R120 (My Review Here)
      5. Chicco Nextfit Zip (