How Do You Determine The Right Roof Box Size?

How Do You Determine Roof Box Size

Roof boxes come in various shapes and sizes, from small to large. But how do you decide which size to purchase?

Roof boxes are containers that are used to transport supplies and goods.

They are commonly rounded or square-shaped and are designed to fit on cars and other vehicles.

If you are the kind of person who loves camping, then a roof box could come in handy, as these containers allow campers to store supplies, without robbing any space from the vehicle’s interior.

So how do you choose the best box size for your car and needs?

In this article, we will teach you how to determine roof box size, while also explaining the necessary dimensions and features you need to consider.

So if you want to purchase the best roof box for your car, this article has everything you need to get started.

Think About What You Need The Roof Box For

Before you buy a roof box, it is important to think about what type of storage you need.

This way, you can make sure that the container is suitable for your purposes.

For example, if you plan on storing tools, you might want to go with a larger roof box than one that is only meant for transporting items.

You should also take into account whether you plan on using the roof box often or just occasionally.

If you intend to use it frequently, you may want to invest in a larger model.

However, if you rarely use it, then you may not have much of an issue with its size.

In most cases, smaller roof boxes are perfect for storing bulky yet lightweight items, such as sleeping bags and pillows.

On the other hand, longer items will need a larger roof box to accommodate their size and length.

Most roof boxes are able to carry a maximum weight of 150 – 165 pounds, which makes them ideal for carrying heavy items.

However, this does not mean that roof boxes are incapable of damage, as overloading the box could cause it to break.

To avoid this, we recommend putting heavier items (such as coolers, water bottles and food bins) inside the vehicle itself.

Examine The Dimensions Of The Roof Boxes

Examine The Dimensions Of The Roof Boxes

Once you have decided what you will use the roof box for, it’s time to take a look at the different boxes and their dimensions.

In most cases, manufacturers will calculate the length, width and height of roof boxes using different methods, which can sometimes result in different data.


Most roof boxes are made to be 6 feet long, which makes them suitable for storing skis and other equipment.

However, if your items exceed 180 cm, then you will need to purchase an extra-long roof box that will fit your supplies.

If you don’t plan on storing lengthy items, then a 6-foot roof box should be enough to meet your needs.


The width of roof boxes varies depending on the manufacturer. Some roof boxes are 4 inches wide, while others can measure up to 8 inches.

It all depends on the item you plan on placing inside. As you have probably guessed, wider roof boxes are capable of holding more equipment.

While narrower boxes are more suitable for small and limited products.

If you want to store other items (such as surfboards) on your roof, then a narrower roof box will do.


Height is a great way to increase the capacity of your potential roof box, as the taller the box is the more you will be able to store in it.

The only drawback is that a tall roof box will also add to the height of your vehicle, which can make it difficult to drive in certain places – such as public garages and drive-through restaurants.

If your vehicle is already considered tall, then you may want to consider how much more height a tall roof box will add.


The length, width and height all come together to determine the overall capacity of the roof box, which can be expressed in a range of measurements.

While most people don’t have a specific number in mind when purchasing a roof box, it is still important to have an idea of the amount of capacity you will need.

The capacity of a roof box can also be attributed to the number of people using it.

For example, a roof box with a 340-liter capacity will be suitable for 2 people.

The Roof Box Needs To Be Compatible With Your Vehicle

When you have found the best roof box for your items, you will need to make sure whether the box is compatible with your vehicle.

This means examining the hatch clearance and how the box will look once it has been attached.

In the section below, we have covered these different factors and how you can use them to purchase the best roof box for your car:

Hatch Clearance

It is very important that you consider the hatch clearance on your vehicle, as some cars with rear doors do not provide enough room to open the trunk and access the roof box.

If you are unable to test the different boxes available, then there are other methods you can use to determine the right size and model.

For example, you can follow the manufacturer’s guidelines and move the front crossbar as far forward as your vehicle allows.

However, it is important to note that some crossbars are not adjustable.

If this method fails, then you can also use a tape measure to calculate the amount of hatch clearance your vehicle has, as well as how much your roof box is allowed.

Compare these measurements to the hatch clearance information on the manufacturer’s website, and you should be able to determine which box size is the best.


When choosing a roof box, you will need to purchase a model that is proportionate to the dimensions of your car.

For example, if you own a large vehicle, then you will need to purchase a large roof box to match.

The same goes if you have a small vehicle, which will need a small roof box to achieve the best results.

While this rule is not set in stone, it still helps to ensure a good look.


In most cases, roof boxes are available in black or silver.

However, some companies do produce boxes in shades of yellow, white and red.

The color you choose comes down to personal preference, however, we would advise purchasing a box that doesn’t clash with the shade of your car.

Final Thoughts

There are many ways to determine the best roof box size for your car.

Whether that be measuring the length, width and height or considering the different items that you intend to use it for.

As long as you find a roof box that meets your needs, you will always be happy with the result.

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