You're probably reading this review because you want to know which can deliver the "three in a row" promise - the Graco Slimfit or the Diono Radian 3RXT?

With the hefty price tag, will the Diono Radian 3RXT win over the Graco Slimfit?

Read on.

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ideal use



Graco Slimfit

Diono Radian 3RXT

Rear-Facing Weight:

5 to 40 pounds

5 to 45 pounds

Rear-Facing Height:

the head must be at least 1" below the handle

Up to 44 inches

Forward-Facing Weight:

22 to 65 pounds

20 to 65 pounds

Forward-Facing Height Limit:

27 to 49 inches

Up to 57 inches

Booster Weight:

30 to 100 pounds

Up to 120 pounds

Booster Height Limit:

38 to 57 inches

Less than 57 inches tall

The Diono Radian 3RXT’s rear-facing weight limit is 5 pounds more than the Graco Slimfit.

It also has a higher forward-facing height limit as well as higher booster weight limit.

Graco SlimFit 3 in 1 Convertible Car Seat | Infant to Toddler Car Seat, Saves Space in your Back Seat, Darcie
Price: $197.99
(As of: 2023/09/17 10:07 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.
You save: $22.00 (10%)
1 new from $197.990 used
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will it fit in my car?


Graco Slimfit
Diono Radian 3RXT
19.88 inches
16.5 inches
25.5 inches
28.5 inches
21.5 inches
16 inches

The Graco Slimfit’s cupholders can be rotated inwards to make the seat “slimmer.” Despite that, the Diono Radian 3RXT is more ideal if you are trying to fit three same car seats in a row.

Diono Radian 3RXT, 4-in-1 Convertible Extended Rear and Forward Facing Convertible Car Seat, Steel Core, 10 Years 1 Car Seat, Ultimate Safety and Protection, Slim Design - Fits 3 Across, Blue Sky
Price: --
(As of: 2023/09/18 12:52 am - 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.
0 new0 used
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Graco Slimfit
Diono Radian 3RXT
Do I need to use a pool noodle/rolled towel?
Easy To Install Rear-Facing?
Easy To Install Forward-Facing?
Easy To Uninstall?

Installing a car seat can be a pain for clueless first-time parents. If an easy installation is your priority, the Graco Slimfit is a safer choice.

Good Convertible Car Seats Of 2023

Consider narrowing down your options by focusing on those made with EPP or EPS foam for impact management. Both materials meet government safety regulations, but EPP foam is more elastic and less brittle than EPS foam, making it better at withstanding multiple impacts and regaining its shape.

Keep in mind that any seat involved in an accident should be replaced, regardless of the foam type.

Good Convertible Car Seats With EPP Foam:

Good Convertible Car Seats With EPS Foam:



Graco Slimfit
Diono Radian 3RXT
Steel Frame:
Five-Point Harness?
Side Impact Tested:
Approved For Airplane Use:
Easy To Buckle And Unbuckle?
the seat

Graco Slimfit

Diono Radian 3RXT

Is The Material Breathable?


Seat Weight:

19.5 pounds

28.1 pounds

Machine Washable Cover?




No-Rethread Harness?



Comes With An Infant Body Support?


Easy To Remove Cover?



10 Years

Comes With A Cup Holder?


Shoulder Harness Has Pads?


Headrest Positions:



Recline Positions:



Air-traveling with a car seat is a little more convenient with the Graco Slimfit given that the Diono 3RXT can be a tank to lug around.

Also, Slimfit’s no re-thread harness is another plus point for parents who appreciate the convenience of just raising the headrest up and down to match the correct harness height of their little passenger.

Although the 3RXT has more headrest positions than the Slimfit, it lacks the ability to adjust its recline position easily as it is fixed. In contrast, the Slimfit offers four different recline positions for added flexibility.


There is an approximately USD 70 price difference between the Graco Slimfit and the Diono Radian 3RXT. The Diono 3RXT is more expensive.

Let’s see what the added cost is for.

  1. The Radian 3RXT has a higher rear-facing weight limit.
  2. The forward-facing height limit is also more generous.
  3. There’s an added 20 pounds more for its booster weight.
  4. It’s way slimmer and more realistic to fit three of it in a row.
  5. It has more headrest positions

Let’s see what Slimfit’s advantages are aside from the monetary savings.

  1. It’s easier to install both in rear-facing and forward-facing mode.
  2. It’s way lighter to bring for air travel.
  3. It has a no-rethread harness.
  4. It has more recline positions


Do You Need More Help To Decide Between

The Graco Slimfit Or Diono Radian 3RXT?


Read My Graco Slimfit Review

See My Diono Radian 3RXT Review


What Do You Think?

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




the graco slimfit or

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

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  1. This is really helpful! What about the ability to clean it? I have a DO know, and it is impossible to get the cushions off. I didn’t even think I could put the car seat back together.

    1. Hi Emily,

      Do you mean “Diono” – how to remove the cushions off the Diono seat? This video might help…

      Kind Regards,

  2. These are the 2 exact car seats im debating on. Let’s say I go with the graco and my child hits the 100lb booster limit, would I have to buy another booster seat or can they go without by then?

    1. Hi Mirba,

      There are few guidelines when deciding if a child no longer needs a booster seat. By the time they reach the 100-lbs mark (around 12 years old, also depending on the genes) you need to answer the following before letting the child seat using the car seat belt alone.

      1. Can they ride with their backs against the vehicle seat?
      2. Are the knees bent at the edge of the vehicle seat?
      3. Lap belt not on belly – but on top of their thighs?
      4. Shoulder belt between neck and shoulder?
      5. Can sit properly (no playing with seat belts)?

      If they can do all five, they can “graduate” using the car seat. If not, it is best to still let them use a booster seat.

      Here’s a helpful illustration from the car seat lady site.

      Ready to graduate from the booster seat?

      I hope this helps.

      Kind Regards,

    1. Hi Summer,

      According to Diono’s website, “as long as you have 51 inches in the back row from vehicle armrest to armrest,” you can install 3 Diono Radian 3RXT in a row. That means you need 17 inches in the middle to accommodate your 3RXT.

      To fit two infant car seats between a 3RXT inside a Subaru Forester, you must know how wide are the infant car seats. Most of the time, you’ll save space by not using the infant car seat base and just install them via the vehicle seat belt.

      To roughly estimate, know the inside dimensions of your vehicle. Add the width of your 2 infant car seats + the 17 inches needed for the Diono Radian 3RXT.

      There are physical stores that would allow you to test-fit a car seat inside your vehicle before purchasing, so that would help, too, if you are not very comfortable with just doing the math.

      I hope this helps.

      Kind Regards,

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