What Size Rooftop Cargo Box Do I Need? Now You Know!

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When it comes to choosing the right size rooftop cargo box, there are a few things you need to take into account. There are many different sizes and shapes of boxes available on the market, but not all of them will fit your vehicle. Therefore, what size rooftop cargo box do you need?

For your rooftop cargo box's size, consider the amount of room you'll need in the cargo box and examine its dimensions. You will also need to make sure that it fits appropriately in your vehicle; you'll want to consider your vehicle's hatch clearance, gross rooftop weight capacity, and what type of goods will go in. 

There are ways to simplify the size of a cargo box. To find out this information, we recommend becoming knowledgeable on the below cargo box-sizing guide:

what type of goods will go in

When it comes to choosing the right size rooftop cargo box, the type of goods you will be transporting is an essential factor to consider. Different types of goods will take up different amounts of space, so you will need to ensure that the cargo box you choose can accommodate whatever you plan on transporting. Otherwise, you may find yourself with a box that is either too small or too large for your needs.

Vehicle dimensions

When choosing a rooftop cargo box, vehicle dimensions are essential because the box must fit appropriately in your vehicle. You'll want to consider your vehicle's hatch clearance, length, and Width. If the Width goes box is too large, it may not fit in your car, or it may be challenging to close your hatch. Too small, and you won't have enough space for all of your belongings.

hatch clearance

Another essential factor to consider when choosing a rooftop cargo box is hatch clearance. This refers to the amount of space between the top of your vehicle's hitch and the bottom of the cargo box. If there is not enough clearance, you will not be able to close the hatch, or you may damage the cargo box. Therefore, it is essential to ensure that you have enough hatch clearance before making your purchase.


Including the above, you'll want to decide on an overall length for your cargo box. Here you'll want to consider the total length of goods you'll transport, along with the rear and front overhang. An overhang on the back of your vehicle could prevent the usage of your boot. Therefore, ensuring it doesn't affect its access is vital. When it comes to the front of the car, you'll want to think about the overall aerodynamics and visibility. If you're having visibility issues from a cargo box, it's way too big. Because of this, ensure it doesn't overhang your front windscreen much.


 Unlike the above, the width needsWidthe considered with your crossbars. To install a cargo box, you must attach it to your roof. Because of this, you'll want to develop knowledge on the maximum installation width for your crossbars.

gross rooftop weight capacity

The gross rooftop weight capacity is the total weight that your vehicle can support on its roof. This includes the weight of the cargo box itself and the weight of the goods you plan on transporting. It is essential to ensure that you do not exceed this weight limit, as it could damage your vehicle or lead to an accident.

In addition, Rooftop cargo boxes have a capacity of about 165 pounds, which is similar to the maximum weight for most vehicles. But, again, double-check with your vehicle's manufacturer to be sure.

When packing your roof box, keep heavier, bulkier objects such as tents, clothing, or sleeping bags to a minimum.


Aerodynamics and visibility 

Aerodynamics and visibility are two important factors to consider when choosing a rooftop cargo box. The aerodynamics of a cargo box will affect the fuel efficiency of your vehicle, and the visibility will affect your ability to see out of the windshield. Therefore, if you are transporting a large amount of cargo, you will want to ensure that the cargo box is aerodynamic and does not impede your visibility.

how to measure roof box size

Measure from the center of your vehicle's front crossbar to the open back hatch at the level of your crossbars with a tape measure. That's all there is to it!

This measurement will give you the length you need to purchase a roof box that perfectly fits your car. And when it comes to roof boxes, getting the perfect fit is essential for ensuring that your belongings are safe and secure while on the road. 

How do you determine roof box size?

The first thing to consider is how many people will be using the box. For example, a 12 cubic ft. box will suffice for two people, but you'll need a larger box if you're planning on packing gear for three or more people.

Another factor to consider is the type of gear you'll be packing. If you're carrying bulky items like camping equipment or snowboards, you'll need a larger box to accommodate them.







12 cubic ft. or less

12-18 cubic ft

20+ cubic ft

Other rooftop Cargo Box size tips and things to Consider

Here are some tips on choosing the right size cargo box and a few things you'll want to consider before making your purchase.

What is the largest size roof box?

The largest size roof box is usually about 22 cubic feet. However, some manufacturers make larger sizes, such as 24 or 26 cubic feet. Therefore, it is essential to ensure that the roof box will fit on your vehicle before purchasing it. You will also want to consider the weight of the roof box when choosing a size. The larger the roof box, the heavier it will be.

What is a good size rooftop box?

A good size roof box is usually about 22 cubic feet. However, some manufacturers make larger sizes, such as 24 or 26 cubic feet. It is essential to ensure that the roof box will fit on your vehicle before purchasing it. You will also want to consider the weight of the roof box when choosing a size. The larger the roof box, the heavier it will be.

What Size Rooftop Cargo Box Do I Need?

The size of the rooftop cargo box you need depends on the amount of space you need to store your belongings. For example, a small car might only need a 10-cubic-foot bag, while a large SUV might need a 22-cubic-foot box. Make sure to measure the length, Width, and Width of your vehicle before choosing a size to ensure that the roof box will fit.

Can a roof box be too big?

Roof boxes can be too large if they do not fit on your car or are too heavy for it to carry. Therefore, it's critical to ensure that the roof box you choose is the right size for your vehicle and that you can safely transport it.

Don't forget other cargo carriers.

After becoming knowledgeable about the above, you can start developing a better understanding of what cargo box size you might need. That being said, if you've discovered that a cargo box might not be suitable. Then, you may want to become familiar with other cargo carriers. Below, we briefly mention the different available types to obtain a more personalized storage device for your situation.

  • Baskets – Cargo boxes are excellent, but you'll be restricted on space. However, this isn't a problem with a basket (also known as a tray). These cargo carriers require you to strap goods onto an open basket for transportation. Although you lose waterproofness because your goods will be open to the natural environment, you can travel with much taller or longer equipment.
  • Bags – The closes cargo carrier to a box is a bag. Bags are great; they look good, are waterproof, and don't require you to be a genius to install. Usually, they're the smallest type of cargo carrier. Therefore, this might be your best option if you've noticed that rooftop boxes are too big for your application.
  • Sport-specific – If you're purchasing a rooftop box to transport one particular equipment style, it might be more beneficial to buy something suited to its needs—for instance, these ski-specific rooftop cargo carriers.

By knowing what's available on the market, you can purchase something more suited to your requirements. After all, that's the end objective.


After reading the above, you should now understand how to reveal the perfect cargo box size suitable for your needs and vehicle. Making sure you get this correct the first time is significant. Failing could result in you having to return your box via mail. If that occurs, the shipment can cost substantial money because of its sheer size.

Additionally to the above, you might want to consider the style and material of a cargo box. The last thing you'll want is your vehicle to lose its aesthetics or your box breaking after a few road trips. If you're going to use a cargo box year-round or for a few months each year, it's undoubtedly worth investing in something more worthwhile than the cheaper models on the market.

About the author 

Vieira Babeker

Hi! I'm Vieira. I've always been interested in different Auto Accessories

My passion here at theroofboxes.com is to provide helpful straight forward clear advice and tips for Automotive Accessories.

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