We compare the Graco SlimFit3 LX vs Diono Radian 3R in this head-to-head comparison article.
The SlimFit3 LX – a new offering from Graco – is the best-designed and most premium car seat available on the market today, the Diono Radian 3R is the world’s most popular 3-across car seat.
How do they compare and which one is better? Read on to find out!
Graco SlimFit3 LX vs Diono Radian 3R: Quick Comparison Overview
- Both the Graco SlimFit3 LX and the Diono Radian 3R are mid-ranged all-in-one car seats with excellent features.
- The Graco SlimFit3 LX is more expensive and the Diono Radian is cheaper for families that have a limited budget.
- Both car seats are slimly designed to fit 3 across in a row. The Graco SlimFit3 LX is 0.25″ inches narrower.
- The Diono Radian 3R has a wider weight range from 5 to 50 pounds (50 lbs vs 40 lbs of Graco SlimFit3 LX).
- The Graco SlimFit3 LX has more recline positions (4 vs 2 of Diono Radian 3R).
- Both car seats have a 10-year lifespan.
- The Graco SlimFit3 LX has additional features for optimal protection and max comfort (including two cup holders).
In this comparison post, we dig in a bit deeper than the specs from the manufacturer, hoping you will like this in-depth review and comparison of the Graco SlimFit3 LX vs Diono Radian 3R and find the one you like most to keep your little one happy.
Graco SlimFit3 LX vs Diono Radian 3R: Side-by-Side Comparison Chart
| Key Features | Graco SlimFit3 LX | Diono Radian 3R |
|---|---|---|
| Rear-facing Height and Weight Limits | 4-50 lbs/ 49" | 5-40 lbs/ 49" |
| Forward-facing Height and Weight Limits | 22-65 lbs/ 49" | 20-65 lbs/ 49" |
| Booster Height and Weight Limits | 40-100 lbs/ 57" | 40-120 lbs/ 57" |
| Adjustable Headrest | 10 positions | 10 positions |
| Recline Positions | 4 | 1 |
| Safety | ProtectPlus Engineering | - |
| Side impact protection | ✓ | ✓ |
| 5-Point Harness | ✓ | ✓ |
| Fabric Breathability | ✓ | ✓ |
| Installation Latch | Push-button InRight™ LATCH | Push Button Latch |
| Front Facing Installation | - | - |
| Level Indicators | ✓ | ✓ |
| Removable Cover | - | - |
| Washable Cover | Machine Washable | Machine Washable |
| Removable Plush Head & Body Inserts | ✓ | - |
| Dimensions | 16.7 in (W) x 24.5 (H) in x 20.7 in (D) | 17 (W)x 16 (D) x 28.5" (H) |
| Width | 16.75 in | 17 in |
| Weight | 19.2 lbs | 25.9 |
| Reviews | 40000+ | 5000+ |
| Price | $279.99* | $199.99* |
Graco SlimFit3 LX vs Diono Radian 3R: Size Limits / Modes
Both the Graco SlimFit3 LX and the Diono Radian 3R are great all-in-one car seats (3-in-1) with a top 57-inch height limit. That’s a very common booster height limit required by most US states to confirm if your child is ready to get out of the car seat or not.
But the Diono Radian 3R overperforms better in the overall size limits. Let’s dive into more details based on the different modes both car seats have.
In rear-facing, the Diono Radian 3R is able to accommodate children between 5 and 50 pounds. The 50-pound simply beats the 40-pound of Graco SlimFit3 LX, even though both are good car seats for extended rear-facing. If the 40-pound top rear-facing limit is good for toddlers around 2 or 3 years old, the 50-pound would be better for older 4 years old preschoolers.
The Diono Radian 3R features a 44-inch top rear-facing height limit, a bit lower than the 49-inch of Graco SlimFit3 LX, but still good to work with the 50-pound weight limit.
Rear-facing size limit is a tie for the Graco SlimFit3 LX vs Diono Radian 3R.
In the forward-facing mode, both car seats perform very commonly as others. Both the Graco SlimFit3 LX and the Diono Radian 3R suit kids between 22 and 65 pounds.
The other difference lies in the booster mode. The Graco SlimFit3 LX has an average 100-pound top booster weight limit, while the Diono Radian is one of the best car seats with a 5-point harness up to 120 pounds. Yes, the Diono Radian 3R is better for taller kids around 7 or 8 years old.
Graco SlimFit3 LX
- 5-40 lbs/49" for rear-facing
- 22-65 lbs/49" for forward-facing
- 400-100 lbs/49" for booster
- 5-50 lbs/44" for rear-facing
- 22-65 lbs/49" for forward-facing
- 40-120 lbs/57" for booster
Graco SlimFit3 LX vs Diono Radian 3R: Installation
Both the Graco SlimFit3 LX and Diono Radian 3R allow for installation with LATCH and seat belt (NOTE: not to use both at the same time).
If choosing to install the car seat with LATCH, both car seats have rigid LATCH connectors. The Graco SlimFit3 LX comes with the InRight LATCH attachment while the Diono Radian features the SuperLATCH.
But the LATCH method has a weight limit. For example, the manufacturer reminds us in the Graco SlimFit3 LX user manual, that ‘Do not install this method for a child weighing more than 45 lb (20 kg)’ in forward-facing mode (the rear-facing mode can’t reach this 45 pounds due to its 40-pound top weight).
This happens on Diono Radian 3R as well. In the user manual, it reads’ Do Not Install by this method for a child weighing more than 35 lbs (15.8 kg)’ in rear-facing installation and ‘Do Not Install by this method for a child weighing more than 40 lbs (18 kg)’ in forward-facing installation.
Luckily, the Graco SlimFit3 LX is equipped with the integrated belt lock-off feature that allows for easy vehicle seat belt installation in forward-facing mode. This ensures an easier and tighter installation with the seat belt.
This feature can be found in the Graco 4Ever DLX 4-in-1 car seat as well, but not included in Graco Extend2Fit.
Graco SlimFit3 LX vs Diono Radian 3R: Safety Standards and Bonus
Both the Graco SlimFit3 LX and Diono Radian 3R passed the crash tests meeting or exceeding the Federal Motor Vehicle Safety Standards 213. This is very basic and mandatory for all car seats sold in America, no matter whether it’s manufactured in the US or not.
When being used in harness mode – rear-facing or forward-facing, both car seats deliver side impact protection. You know the reason why it’s strongly recommended to use the 5-point harness for as long as possible. Harness mode (65 lbs for 4-5 years toddlers) is safer than booster mode (100/120 lbs for big kids).
Both car seats have reinforced steel frames and EPS memory foam for absorbing crash energy to offer optimal protection.
But Graco SlimFit3 LX stands out for its bonus safety feature. It is ProtectPlus engineered to provide protection from front, side, rear, and rollover crashes.
Graco SlimFit3 LX vs Diono Radian 3R: Other Features
Graco SlimFit3 LX vs Diono Radian 3R: Design
Both car seats have a solid build and are durable for a few years.
They are slim car seats for fitting 3 across in the back row, in most vehicles.
The Graco SlimFit3 LX is 16.75″ wide, a bit narrower than the Diono Radian 3R at 17 inches.
The SlimFit3 LX is upgraded from SlimFit which is 19-inch wide, and narrow but not good to fit three across. So the company improved the design to make it slimmer to compete with the Diono Radian series, which is well-known for the 17-inch narrow width to fit 3 across.
Both are not lightweight car seats, even if the Graco SlimFit3 LX weighs only 19.2 pounds (vs 25.9 pounds of Radian 3R).
But the Diono Radian 3R is more portable. It has a foldable design, making it one of the most portable car seats and one of the best travel car seats.
The folding design of Diono Radian 3R (and other Radian car seats) is FAA approved for travel, even good for air travel. You can easily fold the seat pad up and carry it like a backpack.
It’s not a big deal now to navigate through airports with the Diono Radian 3R. The slim design makes it fit well in a narrow window seat on the plane.
The Diono Radian 3R is 4-inch higher (28.5″ vs 24.5″), meaning it may take a bit more room from the front driver or passenger seat. This needs your attention if you’re planning to install the Radian 3R in a window seat in the car. Make sure it can be properly and tightly installed without compromising the comfort of the front row.
The low-profile Diono Radian 3R is more friendly for a toddler to climb in and out.
Both car seats provide multiple color choices. The Katrina color makes the Graco SlimFit3 LX one of the best purple car seats for toddler girls. The pink blossom makes the Diono Radian 3R one of the best pink car seats for girls.
Graco SlimFit3 LX vs Diono Radian 3R: Comfort
Both the Graco SlimFit3 LX and the Diono Radian 3R have breathable seat cover that is made of machine-washable fabrics. Regular cleaning is a good way to keep the car seat a comfortable place for your child to stay.
The Graco SlimFit3 LX earns a bonus point for two aspects.
The seat cover features AirFlow channels that provide improved ventilation to keep your child cool and comfortable.
It comes with a smart seat cover design called ‘Rapid Remove’ that allows you to remove the seat cover in one minute.
The cup holders are another point that the Graco SlimFit3 LX beats the Diono Radian 3R. The former has two large cup holders on both sides. The latter don’t have cup holders but instead with two armrests.
Headrest and Recline Positions
In the comparison of Graco SlimFit3 LX vs Diono Radian 3R, the Graco SlimFit3 LX wins by a narrow margin.
Both car seats allow for 10-position headrest adjustment to grow with your child from birth to tween.
The only difference lies in the recline adaptation. The Graco SlimFit3 LX has four positions while the Diono Radian 3R has only one.
I have to say that both car seats are not that good in this factor. But the Diono Radian 3R is an entry-level budget car seat of the Radian series. The premium siblings have more reclining positions anyway. But the Graco SlimFit3 LX does not have a lot of room to improve. The Graco 4Ever DLX 4-in-1 convertible car seat just supports 6 reclining positions at most.
Usable Life Before Expires
Both the Graco SlimFit3 LX and the Diono Radian 3R are strongly built and durable to last long.
They have the same 10-year lifespan. But the expiry date may vary, depending on the specific date of manufacture. Explore more about the expiry date of Graco car seats and the expiry date of Diono car seats.
Pro tip:
If you’re finding a car seat that can be used for a longer time, get the more popular one.
Popular car seats may be manufactured more recently within one year or less due to the manufacturer’s more efficient and faster supply chain.
One way to check the popularity is to see the reviews on Amazon and other e-commerce platforms.
Popularity and Price
It’s obvious that the Graco SlimFit3 LX is more popular than the Diono Radian 3R.
The SlimFit3 LX is one of the most popular car seats on Amazon, beating other car seats from the same company (like 4Ever DLX) and most car seats from different brands.
It (along with the SlimFit model) received almost forty thousand reviews, far more than the five thousand-around of Diono Radian 3R, even though the Graco SlimFit3 LX is more pricey.
Yes, the SlimFit3 LX is almost $80 more expensive than the Radian 3R ($279.99 vs $199.99). The latter is one of the cheap car seats under $200.
Under the same conditions to fit 3 across car seats, the Graco SlimFit3 LX is higher-priced for additional safety and comfort features.
Aircraft Use
Both the Graco SlimFit3 LX and the Diono Radian 3R are FAA approved for aircraft use in harness mode.
But the Diono Radian 3R is better for air travel. It features a folding design for easy carry and storage.
Graco SlimFit3 LX vs Diono Radian 3R: Verdict
The Graco SlimFit3 LX for Quality
The Graco SlimFit3 LX and Diono Radian 3R have a very similar slim design and size – yet this is where the similarities end. The SlimFit3 LX is a child-friendly and parent-friendly car seat that is packed with a few safety features. The Graco has lots of extras like the AirFlow and Rapid Remove seat cover, ProtectPlus engineering technology, and cup holders.
If you’re looking for an affordable toddler car seat to fit 3 across for road trips, the Graco SlimFit3 LX is very hard to beat.
The Diono Radian 3R for Travel
The Radian 3R is a very cheap, slim, and foldable car seat built by Diono. It has an all-Diono design. It’s a more portable car seat compared to the Graco SlimFit3 LX and will be good for families on the go. The low-profile seat pad and other Diono components make this toddler car seat feel overall good for growing kids.