Diono 4-In-1 Slim Radian 3RXT Car Seat

Last updated date: September 8, 2021

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Diono 4-In-1 Slim Radian 3RXT Car Seat

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We looked at the top Car Seats and dug through the reviews from some of the most popular review sites. Through this analysis, we've determined the best Car Seat you should buy.

Update as September 8, 2021:
Checkout The Best Car Seats for a detailed review of all the top car seats.

Overall Take

This multi-configuration car seat is designed to last a full 10 years as your child grows. With a reinforced steel core, durable materials, an infant insert and 12-position headrest, this seat can easily handle years of use.

In our analysis of 33 expert reviews, the Diono 4-In-1 Slim Radian 3RXT Car Seat placed 4th when we looked at the top 5 products in the category. For the full ranking, see below.

From The Manufacturer

The Diono Radian 3RXT is the original 3 across All-in-One convertible car seat, trusted by over a million parents to protect their child from birth to booster 5 – 120 lb / 2.2 kg – 54 kg.Lovingly engineered with the famous Diono Steel Core and now rear facing for even longer, expect 10 years of safety from just one car seat. The 2020 Radian 3RXT provides safe and comfortable newborn positioning thanks to the new 2-in-1 infant positioning liner with integrated newborn travel high wedge. The wedge creates a lie-flat travel position, pushing baby up to reduce head slump while helping to keep airways open. As your baby grows, simply remove the wedge to allow the 2-in-1 infant positioning liner to give extra infant comfort and toddler support. Designed and engineered with complete rear facing protection, radian 3RXT will keep now your precious cargo rear facing for even longer up to 50 lb / 22.7 kg, approx. 4 years old. Then as they transition to forward facing, the aluminum reinforced headrest can be adjusted to one of 12 positions for safety that grows with them up to 57” / 145 cm tall. Built with a mechanically engineered, reinforced steel core, made from automotive grade high strength steel, the radian is always ready to shield and protect. And when your family grows, the slim fit design will fit 3 acrosin most vehicles without compromising child safety or passenger comfort. As travel experts, Diono have naturally built in super portable features to the radian 3RXT with original fold for easy transport and storage and steel reinforced cup holders to store essential road trip drinks and snacks. The radian is also aircraft certified (FAA approved), so you can take safety with you wherever you go!

Expert Reviews

Expert Summarized Score

5 expert reviews

User Summarized Score

2,204 user reviews

What experts liked

High quality fit and finish everywhere, easy adjustments, an easy to remove and machine washable cover, a great detachable cup-holder, and an easy-fold capability for transport (it's also approved for air travel). The fabric is soft and breathable, and the styling is simple and sophisticated. It's truly a very high quality, safe, reliable, durable, super narrow, and comfortable seat that accommodates not only extended rear-facing, but also a wide range of baby shapes and sizes.
- Mommy Hood 101
Narrow width makes it easy to stack. Foldable for travel.
- Tom's Guide
he Radian 3RXT has color-coded belt paths designed to ease installation, as well as an easy-adjust harness system. It’s FAA-rated for use on airplanes, and folds flat for travel. It also has high safety ratings.
- Parenting Pod
Birth to 120 pounds. Fits 3 across. Steel core.
- Truly Mama
Proven safety record by the manufacturer. Highly durable steel frame. 10-year expiration. Easy SuperLATCH Installation system. Folds flat for easy storage and transport. Various colors of the cover.
- The Safety Restraint Coalition

What experts didn't like

Yes, it's expensive, coming in at about $300. And it's ridiculously heavy at 30 pounds, and we totally prefer a no-rethread harness system.
- Mommy Hood 101
Average crash test performance. Stiff buckles.
- Tom's Guide
Many parents have complained that the seat is hard to install, and the angle may not be good for smaller babies. Also, some kids may outgrow the seat early – and the seat itself is relatively heavy, at over 27 lbs.
- Parenting Pod
Higher price point. Not ideal for travel. Angle adjuster may be needed; sold separately.
- Truly Mama
A bit heavy. May limit legroom for front passengers. Non-intuitive installation. Single recline angle.
- The Safety Restraint Coalition

An Overview On Car Seats

Choosing the correct car seat is one of the most crucial decisions a parent can make for their child. A good car seat should support the fragile parts of your child’s body. It should also have soft materials on the surfaces the child will be touching to ensure comfort during car rides.

There are three general types of car seats: rear-facing seats for younger children, forward-facing seats and booster seats for older children. Some car seats are convertible and can switch between rear- and forward-facing. There are also all-in-one models that can also be booster seats.

Rear-facing seats cradle and support the fragile spinal columns of newborns and infants throughout a ride and in the event of a crash. A rear-facing configuration is the safest for all children until they outgrow the car seat’s rear-facing size and weight ratings.

Besides configuration, two other important considerations you should have in mind when choosing a car seat are ease of use and whether the car seat fits your vehicle. You should be able to install your car seat correctly every time, without any uncertainty.

The Car Seat Buying Guide

  • Test out your car seat in your vehicle before buying it, or make sure you can return it if it doesn’t work to your liking.
  • The configuration of your car may not accommodate some car seats, so do a little research before buying.
  • Keep in mind where in the car the car seat will be so you can ensure it is cleaned regularly.
  • As your child gets older, let them participate in the shopping process by letting them pick colors and patterns on your next model of car seat. This will give them a closer connection to the seat.