Buying a roof box is a great way to increase the storage capacity of your car - and may be especially useful for long road trips where you don't want luggage on passengers' laps or otherwise obstructing the driver's view.

It's also a quick and economical alternative to replacing your vehicle with one that has a larger boot.

It’s possible to purchase a roof box with as much capacity as a Skoda Octavia's boot - for just a few hundred pounds.


What items are normally carried in roof boxes?

Items like sleeping bags, sports equipment and tents are often carried in roof boxes.

Usually, more important items are stored in the boot and less important ones in the roof box.

Man putting items into car roof box

How do I choose the best roof box for my needs?

Capacity: What size roof box do I need?

How big a roof box do I need? It's a common question.

For most families it makes sense to buy the biggest capacity box you can find. On the other hand, if you want to carry a roof-mounted bike rack on one side of the vehicle, you can buy a half-sized roof box that can occupy the other side. 


Durability: How durable is the roof box?

Cheaper roof boxes will be less durable - because they use thinner plastics - and cause more wind noise. If you can, invest in a higher quality roof box.


Roof box fitting type

Ensure your chosen roof box fitting is compatible with your roof rack system.

Consider Paying extra for a quick-release system (a godsend in wet or cold weather).


Opening type

If you want quick, easy access to the entire box, consider a dual opening or hinged model.

Conversely, a side-opening box will only afford access to the side.


Roof box size guide

Roof boxes generally fall into three categories:

  • 1/2 width - comparable to a mid-size car boot
  • 3/4 width - comparable to a large car boot
  • Full width - comparable to a large estate car boot

Car Roof Rack

How do I attach a roof box to my car?

To fit a roof box, you first need to install roof bars. The most common types are:


Square steel bars

These are strong, durable and affordable. However, they can impact fuel efficiency more than alternative roof bars.


Aluminium aero bars

Aero bars are a more aerodynamic alternative to square steel bars. Their T-track system means the full width of the roof can be used.



These popular proprietary roof bars maximise the available roof space, and are extremely aerodynamic. They are also up to 90% quieter than regular aero bars.


Roof box mounting systems

You'll need a way to connect the roof bars to the roof box.

The two most common mounting systems are:

  • U-bolts - these are U-shaped bolts fit around the roof bar T-section and connect to the inside of the roof box.
  • Power click mount - these 'claw' systems are even quicker to mount than U-bolts.


Can I fit roof bars myself?

Yes, it is possible to fit roof bars yourself. Alternatively, some garages offer this service for a small fee.

The items needed to fit (most) roof bars are sold separately because requirements differ between models.


Items needed to fit roof bars:

  • The roof bars
  • Foot packs for fitting to the roof bars
  • Fitting kits, which connect the bar feet to the rooftop


Do all bars fit my car?

Most bar types fit most cars, but consult your handbook, manufacturer or a suitable online tool to double check this.

Some bars have weight restrictions, which may make them unsuitable for higher-capacity roof boxes.

Weight restrictions range from 50 - 100 kg.

However, your vehicle's roof may also have a weight restriction - which is normally lower than the roof bar's limit. It is critical you check this - especially if you plan to carry heavy items in your roof box.


Do roof boxes affect fuel economy?

Yes, roof boxes do affect fuel economy due to the extra wind resistance they cause. However, modern roof boxes are far more aerodynamic than models of the past, so you would only expect around a 5% increase in fuel consumption.

Today’s roof boxes feature tapered front ends which reduce wind resistance (or ‘drag’) as much as possible.

That said, if you fill your roof box with heavy items, that could have a more dramatic effect on your fuel consumption.

Opting for a low-profile roof box can also aid aerodynamics and minimise fuel consumption.


Are roof boxes worth it?

Overall, roof boxes allow you to optimise your car’s storage while increasing capacity - to the point where you have an extra boot’s worth of space.