Diono Radian 3RXT Review

The Diono Radian 3RXT Convertible Car Seat is one of the best all in one car seats available on the market today. It is suitable for newborns, toddlers, and older children.

If you’re looking for a narrow car seat for your vehicle, the Radian 3RXT car seat is a perfect choice. In fact, their clever design allows you to install 3 car seats across in most mid-sized vehicles.

Our Diono Radian 3RXT car seat review will help you decide if this is the car seat for your baby.

Diono Radian 3RXT Convertible Car Seat

Diono Radian 3RXT All-in-One Convertible Car Seat is one of the best narrow car seats that you can purchase for your newborn or toddler.

It is an updated model from its predecessor, the Diono Radian RXT. There are some impressive features with the Diono Radian 3RXT, including its steel-reinforced frame and advanced safety features.

What we love about the Radian 3RXT car seat is that it’s one of the few car seats that allows your baby to sit rear facing for an extended time – up until 45 pounds!

This Diono 3RXT car seat includes their original Diono nesting insert to keep your newborn secure and cozy.

It also has a thick padded cover and a memory foam seat bottom, making the car seat super comfortable.

Radian car seats also fold flat, making it one of the best portable car seats. They are FAA approved and certified for use on aircraft, making it one of perfect for easy travel.

Its SuperLATCH system makes installation easy and secure, making it a parent’s dream car seat. Installing car seats can be painful and stressful if you can’t figure out how to do it correctly.

Diono 2019 Radian 3RXT All-in-One Convertible Car Seat, Black

Diono Radian Series

Diono Radian 3RXT vs 3RX vs 3R

Aside from this Diono Radian 3RXT, there is also the Diono Radian 3R and Radian 3RX. The Radian line of seats are known for being narrow car seats that can fit 3-across.

Is there a difference between the Diono Radian 3RXT, 3RX, and 3R?

All three of them have the same safety features. There are just a few extra features that distinguish them from one another. The 3 RXT is the high-end model whereas the 3 R does not come with any added accessories.

Diono 3R vs. 3RX

The weight limit for the 3R in the rear facing position is 40 lbs whereas it is 45 lbs for the 3RX. The weight limit for the 3R in the booster position is 100 lbs whereas the Diono 3RX fits children up to 120 lbs!

Many parents find the higher weight limits of the 3RX worth the extra cost. Unlike the 3R, the 3RX includes an infant insert and cupholder.

Diono 3RX vs 3RXT

The Diono 3RX and 3RXT has the same weight limits for all 3 positions – rear, facing, forward facing, and booster, fitting children from 5 lbs all the way to 120 lbs.

The main difference between the two models is that the 3RXT comes with EPS foam-surrounded headwings, which offers extra protection. Many parents find the 3RXT’s added side impact protection and adjustable headrest worth the extra cost.

Like the 3RX, the 3RXT also comes with an infant insert and cup holder.

Diono Radian 3RXT Dimensions

Below are the Diono Radian 3RXT measurements and limits:

  • Diono Radian 3RXT measurements: 16.14″ x 16.93″ x 28.35″
  • Diono Radian 3RXT rear facing weight: 5-45lbs
  • Diono Radian 3RXT rear facing height: 44″ or Until the child’s head is 1 inch below the top of the car seat
  • Diono Radian 3RXT forward facing weight: 20-65lbs
  • Diono Radian 3RXT forward facing height: Until the child reaches 57″ tall. Ensure child’s shoulders are not above top harness slots
  • Diono Radian 3RXT booster weight: 50-120lbs
  • Diono Radian 3RXT booster height: 40-57″ tall

The Diono Radian 3RXT width is about 17″ wide at its widest point and weighs about 26 lbs.

Diono Radian 3RXT Safety

Diono is a well known and trustworthy brand, with child safety as top priority.

Diono car seats are built from high quality materials with a full steel reinforced frame and aluminum reinforced sides. They do not skimp on safety features.

It is a heavy car seat but it is worth the extra weight. It does not have a cheap feel to it, unlike some other car models.

Like all car seats on the market, the Diono Radian 3RXT is crash tested and meets federal crash-test safety requirements. All their seats go through rigorous testing protocol that simulate side impact crashes.

Diono Radian 3RXT Stroller

Since Diono Radian 3RXT is a convertible car seat, and convertible car seats are not designed to be easily removed from the vehicle once installed, there is no compatible stroller.

Convertible car seats are meant to be stationary and are not designed to be used with a stroller or a stroller base.

Diono Radian 3RXT Base

The Diono Radian 3RXT car seat has a built-in base. A separate base is not necessary.

Diono Radian 3RXT Installation

According to the National Highway Traffic Safety Administration, as much as 50% of car seats are installed incorrectly!

Adjusting the seat and installing the Diono Radian 3RXT isn’t as easy as some other of the car seats, but it gets easier after you’ve done it a few times!

With the Diono’s SuperLATCH system, you’ll hear an audible click that will let you know when connectors are locked in safe.

One disadvantage is that you need to remove the seat and rethread the straps to adjust their height.

If you’re having difficulty fitting 3 across, some parents recommend using seat belt installations for all the seats, as the position of the LATCH anchors could make the fit too snug.

Follow the Diono Radian 3RXT manual and keep it in a safe place in case you need to refer back to it in the future. You should also be able to look up the manual on the company website.

Diono Radian 3RXT Features

Below are the Diono Radian 3RXT specifications and features:

  • Diono Radian 3RXT Weight Limit: This Diono Radian 3RXT car seat fits children from 5-45lbs rear-facing, 20-65lbs forward-facing and 50-120lbs in booster mode
  • Diono Radian 3RXT Height Limit: Up to 49″ inches tall
  • Its narrow design allows you to fit 3 across in most mid-sized to large cars
  • Allows for extended rear facing – until 45 pounds
  • Full steel reinforced frame and aluminum reinforced sides
  • Easy SuperLATCH connectors
  • One-pull harness tightening
  • Lined with energy absorbing foam
  • 12-position adjustable headrest
  • 5 harness slot heights
  • 3 crotch/buckle strap positions
  • Includes infant insert and a body support insert
  • Soft, plush fabric
  • Memory foam seat bottom
  • Low side profile so toddlers can easily get in and out of the seat by themselves
  • Removable cup holder
  • The car seat folds flat for easy storage and travel
  • FAA approved for air travel in both rear-facing and forward-facing modes

Its padded cover and memory foam seat bottom makes this Radian seat a pretty comfortable car seat. You cannot wash the memory foam but the cover is machine washable in cold water. Use gentle detergent on gentle cycle and lay flat to dry.

After reading this Diono Radian 3RXT convertible car seat review, hopefully you have an idea of whether this convertible car seat is right for your baby.

If you’re looking for a Diono Radian 3RXT sale, you can check Amazon. You can read the Diono Radian 3RXT reviews before making your final decision.

When does the Diono Radian 3RXT car seat expire?

Diono Radian 3RXT car seats have an expiration of 10 years. The expiration date is listed on all of their car seats.

Is Diono car seat worth the price?

Yes! Considering this high quality car seat, paying a premium for the only car seat you may ever need is worth it. Instead of having to buy multiple seats, you just need to pay once!


Overall, the Diono Radian 3RXT is one of the best convertible car seats on the market. If you have a mid to large sized vehicle and you are in the market for a seat that can fit 3 across, the Diono Radian car seat is one of the best options for you.

For more, check out some other best convertible car seats.

Booster Seat Age

Some common questions we get are “can a 4 year old sit in a booster seat?” or “can I put my 5 year old in a booster seat?”

First off, don’t rush to move your child to a booster seat before they are ready. If you can safely keep your child in their forward-facing harness car seat for longer, do so.

Your child ideally should be at least 5 years old, although some boosters start at age 4.

The American Academy of Pediatrics recommends that children use a 5-point harness car seat until they reach the maximum height or weight of that car seat.

Once your child has outgrown the weight or height limit of their forward-facing harness car seat, which is generally between 40 and 65 pounds, they can sit in a belt-positioning booster seat.

Every car seat has its own height and weight limits so you need to refer to the manufacturer’s manual for your specific limits.

How to Know When Your Child is Ready For a Booster Seat

So how do you know when your child is ready for a booster seat?

To sit in a booster seat, your child should:

  • Have exceeded the height or weight limits on their harnessed car seat
  • Ideally be at least age 5, although some boosters start at age 4
  • Weigh at least 40 pounds
  • Be mature enough to sit properly in the booster without slouching, leaning forward, or playing with the vehicle seat belt for the entire car ride

To test that your child is ready to use a booster seat, have him sit in the booster seat and ensure that he is all the way against the back of the seat, with his knees bending at the edge of the seat cushion. If he is too small for the booster seat, his legs will stick straight out and he may be slouching, both of which can be dangerous.

How do you know if your child has outgrown his forward-facing car seat?

  • He has reached to maximum weight or height allowed for his seat with a harness.
  • His shoulders are above the top harness slots.​
  • The tops of his ears have reached the top of the seat.

Booster Seat Tips

When your child is in the booster seat, ensure that the lap belt crosses his hips, not his belly, and touches the top of his thighs. Make sure that the shoulder belt lands on his shoulders, not his neck or upper arm, and crosses the center of his chest. The shoulder belt should never be placed under your child’s arm or behind his back.

Always make sure you use both the shoulder and lap belts with a booster seat. Never use only the lap belt with a booster seat. You can use a booster seat until the vehicle seat belt can correctly fit your child without the use of the booster seat.

Remember, each time you move your child to the next seat, there is a reduction in the level of protection for your child, so don’t rush to move him!

Booster Seat Age NY

You should check your own state’s specific law. For the State of New York as an example, booster seats are for children who are 4-8 years old, weigh 40-80 pounds, and are less than 4 feet, 9 inches in height.

Many states, such as California, do not specify a booster car seat age requirement. As long as your child follows the checklist that we have provided above, you can move him to a booster seat.

Combination Car Seats

If your child has outgrown the forward-facing car seat but is not ready to stay seated properly in a booster seat using the lap and shoulder belt, look into combination car seats, otherwise known as toddler booster car seats.

Combination car seats have a 5-point harness that you can later remove and use as a belt-positioning booster car seat. This will provide your child the best protection as you get to keep him in a harnessed car seat for longer. Most children can continue using the harness until they weigh at least 40 pounds.

One of the best combination car seats is the Cosco High Back Booster Car Seat, a 5-point harnessed car seat that converts to a belt-positioning booster seat. The seat protects harnessed children from 22-40 lbs and belt-positioned children from 40-80 pounds.

Other top harnessed booster car seats include the Chicco MyFit Harness + Booster Car Seat and Graco Tranzitions 3 in 1 Harness Booster Seat.

Chicco MyFit Harness + Booster Car Seat, Canyon

Booster Car Seats

There are 2 types of booster seats: booster seat with high back and backless booster seat. They do not come with a harness but are used with both lap and shoulder seat belts in your vehicle.

You can read more about the types of booster car seats here.

Chicco GoFit Backless Booster Car Seat - Shark                    Evenflo Big Kid Sport High Back Booster Car Seat, Rainier

If you’re in the market for cheap booster seats, read our top Booster Car Seats Under $100.

If you’re in the market for a narrow booster seat, especially if you have a small vehicle, check out our top narrow booster car seats.

Slim Booster Seat

Car seat guide: You can find the slimmest booster seat via slim booster seat if you want to fit 3 kids in the back seat.