Britax Car Seat Size Chart by Model, Weight and Age

by Julia

When it comes to choosing the perfect car seat for your infant, there are a lot of factors to consider. To make things a little bit easier, we’ve put together the Britax car seat size guide by model and weight or age of your children. We’ll walk you through all of the features and benefits, and help you decide if this seat is right for your family. 

Britax Car Seat Size Chart by Model, Weight and Age size-charts.com
Photo by Wesley Tingey on Unsplash

The Britax infant car seat is designed to withstand the impact of a car accident or a fall without causing injury to your child. It meets all U.S. safety standards and is made of soft, flexible foam that is known for its shock absorption and durability. 

With so many different brands and models on the market, how do you know which one is right for you? 

Table of Content of Britax Car Seat Sizing

Britax Car Seat size Comparison Chart

To understand the growth curves for boys or girls, click the links

TypeB-SAFE 35B-SAFE ULTRAENDEAVOURS
Weight Capacity4 – 35 lbs, 1.8 – 15.8 kg4 – 35 lbs, 1.8 – 15.8 kg4 – 35 lbs, 1.8 – 15.8 kg
Layers of Side122
Impact Protection   
Adjustable Harness Positions No-Rethread, 4No-Rethread, 6
Recline Positions333
Impact Stabilizing✓✓✓
Steel Frame✓✓✓
Energy-Absorbing Base✓✓✓
Energy-Absorbing EPS Foam✓✓✓
LUAS ConnectorsEasy On/Off AnchorsEasy On/Off AnchorsEasy On/Off Anchors
Installation Level IndicatorsDual Auto-LevelDual Auto-Level IndicatorsDual Auto-Level Indicators
Removable Comfort PadsHead & Shoulder PadsBody Pillow &Shoulder PadsBody Pillow & Shoulder Pads
Travel System Compatible✓✓✓
Flip-Forward Belly Pad  ✓

Britax Car Seat size Charts by Models, Age and Weight

Baby size chart

Car Seat ModelBaby ageBaby weightRear facingForward facingDimensions cm (HxWxL)Dimensions inches (HxWxL)Car seat weight
 
BABY-SAFE iSENSE BUNDLE0 – 15 months0 – 13 kg40 – 83 cmNO58 x 44 x 6722.83 x 17.32 x 26.384.8 kg
BABY-SAFE iSENSE0 – 15 months0 – 13 kg40 – 83 cmNO58 x 44 x 6722.83 x 17.32 x 26.384.8 kg
BABY-SAFE 3 i-SIZE BUNDLE0 – 15 months0 – 13 kg40 – 83 cmNO58 x 44 x 6722.83 x 17.32 x 26.384.6 kg
BABY-SAFE 3 i-SIZE0 – 15 months0 – 13 kg40 – 83 cmNO58 x 44 x 6722.83 x 17.32 x 26.384.6 kg
BABY-SAFE i-SIZE FLEX BASE0 – 15 months0 – 13 kg40 – 83 cmNO72 x 44 x 6428.35 x 17.32 x 25.208.7 kg
BABY-SAFE ISOFIX BASE0 – 13 months0 – 13 kg40 – 83 cmNO77 x 32 x 6730.31 x 12.60 x 26.385.3 kg
PRIMO BASE0 – 13 months0 – 13 kg40 – 83 cmNO66 – 82 x 32.5 x 7025.9 – 32.2 x 12.7 x 27.54.7 kg

 Baby + toddler size chart

Car seat modelBaby ageBaby weightRear facingForward facingDimensions cm (HxWxL)Dimensions inches (HxWxL)Car seat weight
DUALFIX iSENSE BUNDLE3 months – 4 years18 kg61 – 105 cm76 – 105 cm59.4 x 44 x 46.523.39 x 17.32 x 18.31
DUALFIX iSENSE3 months – 4 years18 kg61 – 105 cm76 – 105 cm59.4 x 44 x 46.523.39 x 17.32 x 18.315.3 kg
DUALFIX 3 i-SIZE3 months – 4 years18 kg61 – 105 cm76 – 105 cm59.4 x 44 x 46.523.39 x 17.32 x 18.315.2 kg
DUALFIX 3 i-SIZE BUNDLE3 months – 4 years18 kg61 – 105 cm76 – 105 cm59.4 x 44 x 46.523.39 x 17.32 x 18.315.2 kg
BABY-SAFE 2 i-SIZE0 – 15 months0 – 13 kg40 – 83 cmNO58 x 44 x 6722.83 x 17.32 x 26.384.8 kg
PRIMO0 – 13 months0 – 13 kg40 – 83 cmNO53.5 x 44 x 62.521.06 x 17.32 x 24.614. kg
DUALFIX i-SIZE0 months – 4 years0 – 18 kg40 – 105 cm76 – 105 cm48 x 44 x 7418.90 x 17.32 x 29.1315 kg
DUALFIX M i-SIZE3 months – 4 years18 kg61 – 105 cm76 – 105 cm48 x 44 x 7418.90 x 17.32 x 29.1315 kg
SWINGFIX M i-SIZE3 months – 4 years18 kg61 – 105 cmNO48 x 44 x 7418.90 x 17.32 x 29.1314.5 kg
DUALFIX 2 R0 months – 4 years0 – 18 kg9-18 kg0 -18 kg53 x 45 x 7020.87 x 17.72 x 27.5614 kg
FIRST CLASS PLUS0 months – 4 years0 – 18 kg9-18 kg0 -13 kg65 x 45 x 5925.59 x 17.72 x 23.238.4 kg
DUALFIX Z-LINE3 months – 4 years18 kg61 – 105 cm76 – 105 cm48 x 44 x 7418.90 x 17.32 x 29.1315 kg

 Toddler size chart

Car seat modelBaby ageBaby weightRear facingForward facingDimensions cm (HxWxL)Dimensions inches (HxWxL)Car seat weight
TRIFIX 2 i-SIZE15 months – 4 years9 – 22 kgNO76 – 105 cm65 x 45 x 5465 x 45 x 54 cm
KING II LS9 months – 4 years9 – 18 kgNO9 – 18 kg67 x 45 x 5426.38 x 17.72 x 21.2610.3 kg
DUO PLUS9 months – 4 years9 – 18 kgNO9 – 18 kg64 x 45 x 4625.20 x 17.72 x 18.119 kg

Toddler + child size chart

Car seat modelBaby ageBaby weightRear facingForward facingDimensions cm (HxWxL)Dimensions inches (HxWxL)Car seat weight
ADVANSAFIX i-SIZE15 months – 12 years NO76 – 150 cm60 – 83 x 44 x 4723.6 – 32.6 x 17.3 x 18.5
ADVANSAFIX M i-SIZE15 months – 12 years NO76 – 150 cm60 – 83 x 44 x 4723.6 – 32.6 x 17.3 x 18.511 kg
ADVANSAFIX IV R9 months – 12 years9 – 36 kgNO9 – 36 kg60 – 83 x 44 x 4723.6 – 32.6 x 17.3 x 18.511 kg
MAX-WAY PLUS9 months – 6 years9 – 25 kgNO9 – 25 kg64 x 45 x 6425.20 x 17.72 x 25.207 kg
EVOLVA 1-2-3 SL SICT9 months – 12 years9 – 36 kgNO9 – 36 kg61 – 86 x 51 x 4824.0-33.8 x 20.0 x 18.98.6 kg
EVOLVA 1-2-39 months – 12 years9 – 36 kgNO9 – 36 kg61 – 86 x 49 x 4824.0-33.8 x 19.2 x 18.98 kg
MAX-WAY9 months – 6 years9 – 25 kgNO9 – 25 kg64 x 45 x 6425.20 x 17.72 x 25.207 kg
MULTI-TECH III9 months – 6 years9 – 25 kgNO9 – 25 kg62 – 72 x 45 x 4824.4 – 28.3 x 17.7 x 18.910.5 kg

 Child size chart

Car seat modelBaby ageBaby weightRear facingForward facingDimensions cm (HxWxL)Dimensions inches (HxWxL)Car seat weight
KIDFIX i-SIZE3.5 years – 12 years15 – 36 kgNO100 – 150 cm63 – 83 x 48 x 4224.8 – 32.6 x 18.8 x 16.5
KIDFIX M i-SIZE3.5 years – 12 years15 – 36 kgNO100 – 150 cm63 – 83 x 44 x 4224.8 – 32.6 x 17.3 x 16.56.5 kg
KIDFIX III S3.5 years – 12 years15 – 36 kgNO15 – 36 kg67 – 85 x 54 x 4326.3 – 33.4 x 21.2 x 16.98 kg
KIDFIX III M3.5 years – 12 years15 – 36 kgNO15 – 36 kg67 – 85 x 54 x 4326.3 – 33.4 x 21.2 x 16.97.5 kg
KIDFIX 2 S3.5 years – 12 years15 – 36 kgNO15 – 36 kg67 – 85 x 54 x 3926.3 – 33.4 x 21.2 x 15.37.2 kg
KIDFIX 2 R3.5 years – 12 years15 – 36 kgNO15 – 36 kg67 – 85 x 48 x 3926.3 – 33.4 x 18.9 x 15.37 kg
KIDFIX SL3.5 years – 12 years15 – 36 kgNO15 – 36 kg67 – 85 x 51 x 3826.3 – 33.4 x 20.1 x 14.96.4 kg
KID II3.5 years – 12 years15 – 36 kgNO15 – 36 kg67 – 85 x 51 x 3826.3 – 33.4 x 20.1 x 14.95.8 kg
DISCOVERY SL3.5 years – 12 years15 – 36 kgNO15 – 36 kg67 – 85 x 44 x 4526.3 – 33.4 x 17.3 x 17.74.3 kg
ADVENTURE3.5 years – 12 years15 – 36 kgNO15 – 36 kg67 – 85 x 44 x 4426.3 – 33.4 x 17.3 x 17.33.9 kg
KIDFIX Z-LINE3.5 years – 12 years15 – 36 kgNO15 – 36 kg67 – 85 x 48 x 4326.3 – 33.4 x 18.9 x 16.97.5 kg

A chart will help you make sure that the car seat is the correct size for your child. You’ll find that Britax offers a variety of infant car seats in different sizes (britax infant car seat dimensions), so be sure to choose the right one. 

FAQ about Britax car seat sizes

Why Choose a Britax Infant Car Seat?

Britax is a trusted brand for infant car seats. When it comes to safety, you can’t go wrong with Britax. All of their seats undergo rigorous testing to ensure that they meet or exceed safety standards. In addition, Britax seats are designed to be easy to use, with features like one-handed recline and buckle release. 

Choosing a Britax car seat also means you have a wide range of options. They have seats that are compatible with most popular strollers, and they even have a line of convertible seats that can be used from infancy through childhood. 

So, why choose a Britax infant car seat? Because when it comes to safety and convenience, Britax is hard to beat. 

Choosing the right Britax car seat sizes

When you’re thinking about buying your Britax infant car seat, you might be overwhelmed by the wide variety of choices out there. In the end, though, the three most important things to consider are the brand, the model, and the size. Size is very important because regardless of the brand or model you go for, you still have to make sure that it is a size that will be comfortable for your child. Otherwise, a seat that is oversize or undersize can easily injure your child or make them uncomfortable, meaning the seat will not serve its purpose at the end of the day. 

The best way to find and buy the correct size is by using the Britax infant car seat size chart. The right chart is the ultimate helper when it comes to determining the Britax infant car seat size, or indeed any brand that you might be deciding to buy. Each brand have their own charts as per its range of car seats. So make sure you are using the right chart. Don’t use the chart of a brand then go buying the car seat from a different brand. This will mix you up and you might end up buying the wrong size. 

How to Install and use a Britax Infant Car Seat?

When it comes to britax infant car seat installation, there are a few things you need to know in order to use and install it properly. 

First, always read the car seat’s instructions carefully. This is where you find everything important that you need to know about the seat, including britax infant car seat size adjustment, working with britax infant car seat size accessories, britax infant car seat size base installation, etc. 

To install properly, use the car seat’s base when installing it in your car. The base gives you a stable foundation and makes it easier to secure the car seat in place. 

What is the weight limit for Britax infant car seat? 

When it comes to britax infant car seat size limits, you need to pay attention to what the manufacturer recommends. For example, the weight limit for Britax infant car seat is 35 pounds or about 15.9 kgs. It is not recommended for children who weigh more than this. If your child weighs more, please consult your doctor for other car seats that may be better suited for your child or check other options to get the right choice. But never try to force it against a weight limit as advised by the manufacturer. 

Britax’s infant car seat size limits are in line with international standards, and are commonly accepted as the industry norm. In most cases, the Britax infant car seat size limits apply to the car seat from birth to around 8 years old, which again is the common standard in the industry. Britax recommend that the rear-facing child car seat should not exceed the weight limit of 23kg / 50lbs and front-facing child car seat should not exceed the weight limit of 20kg / 44lbs (Britax, 2012). Although these limits are not always observed, the weight and size of a child car seat are important factors to consider when choosing a seat that is best for your child.

Remember that the seatbelt should be snug, but not cutting into your child’s neck. If the seat belt is cutting your child’s neck, it is too loose.

Other considerations in addition to britax infant car seat size by weight include britax infant car seat size by age and also height. 

Do you need an infant insert for Britax car seat?

Yes you need but it’s mostly optional for babies weighing 4-11 lbs and most of their car seats come with it already in place. The insert ensures that the car seat is safe and comfortable for your child while they are in it. This makes it safer for your child to travel in the seat when they aren’t using the seatbelt. They’ll also provide you with a car seat belt that fits around the insert. This way, you can use the seatbelt in your car without having to put your child in a child seat that isn’t as safe.

How long can you use Britax infant car seat?

There are a few things to keep in mind when it comes to how long you can use a Britax infant car seat. The first thing to consider is the size of your child. The car seat will only be usable until your child reaches the height or weight limit for that particular seat. 

The second thing to keep in mind is the expiration date of the car seat. All car seats have an expiration date, and it’s important to make sure you’re not using an expired car seat. The expiration date is usually about 6 years after the date of manufacture, but it’s best to check your specific seat’s expiration date. 

The third thing to consider is the size of the base. The base is what attaches the car seat to your car. The base has an expiration date as well, and you should always replace the base if it expires.

Are all Britax bases the same?

Britax infant car seats have different bases to suit your vehicle. Some bases are made to fit in vehicles with a flat floor, while others are designed to work in vehicles with a raised floor. Some bases are also made to keep the car seat in place when your vehicle is in motion, while others are designed to keep the car seat in place even when your vehicle is parked. Some bases are also made to fit in vehicles with a rear-facing only seat, while others are designed to fit in vehicles with a forward-facing seat.

Britax car seat sizes explained (dualfix video)

DUALFIX M i-Size – How to fit by Britax Römer Europe

Conclusion

We understand that choosing a car seat for your infant can be a daunting task. With so many different options on the market, it can be hard to know which one is the best for your child. But with a little bit of patience and with the help of this guide, you can find the perfect seat for your little one. 

Britax infant car seat seats are definitely designed to provide your child with maximum safety and comfort while they are in the car. And, thanks to its many features, the Britax infant car seat is a great choice for any parent. So yes, give it a try!

Remember to always buckle your child in using the five-point harness system. This will keep them safe and secure while you’re driving. Finally, never leave your child unattended in a car seat. Even if you’re just out for a quick run into the grocery store, remember to take your child with you or have someone to keep an eye on them.  

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