Getting ready for a trip, the suitcases are packed, but the trunk is already full before you’ve even loaded the essentials? Don’t worry. A car roof box is the perfect solution to gain the extra space you need and travel comfortably, without items at the passengers’ feet.

Find the right size and shape

The first step is to calculate the capacity in liters, as well as the shape that suits you:

• Up to 350 - 400 liters: The ideal size for small and compact cars. It easily fits 2-3 large bags or a baby stroller.

• From 450 liters and up: For large SUVs, station wagons, and families that bring along... the whole house.

• Long or wide? If you want to place a bike rack or ski poles next to the roof box, choose a long, narrow one. If you want to store large, hard suitcases, prefer a shorter and wider one.

Tip for the trunk: Before buying a very long roof box, make sure it won’t extend so far to the rear that it prevents your car’s rear door from opening fully.

Bars and Mounting Kit: How Will It Be Supported?

The roof box never rests directly on sheet metal. You need a roof system that consists of:

• The bars: Aluminum ones are more aerodynamic and quieter on the road, while steel ones are more economical but cause more wind whistling.

• The feet and the Kit: These are the components that connect the bars to your car. Here you need to pay attention to what kind of roof you have. Is it completely bare? Does it have ready-made mounting points with caps (fixpoints)? Or does it have rails running along the length (integrated or raised)? Every car needs its own specific kit.

The big secret about weight

Many people make the mistake of loading the roof box until it won’t close. Be careful: every car has a maximum weight limit that its roof can support (you can find it in the manufacturer’s manual; it is usually 50–75 kilos). This limit must include the weight of the bars (about 5 kilos) and the weight of the empty roof box itself (about 15 kilos). The remaining weight is what you can put in as luggage. 

That’s why we always put light items in the roof box (clothes, jackets, sleeping bags), and heavy items go below, in the regular trunk.

How will you open it?

You will find roof boxes with single opening (they open only from one side) and with double opening (they open from both the left and the right). If your budget allows it, choose the double opening. It makes things much easier when you park on narrow streets and helps you tighten the mounting screws much more easily.

Do you have an electric car? Check out towbar cargo boxes

If you drive an electric vehicle (EV) or simply want the lowest possible consumption, a roof cargo box will cut around 15-20% of your range due to aerodynamics. The solution? towbar cargo boxes. These are special boxes that mount at the rear of the car, are sheltered from the wind, and have almost no effect on your consumption or battery.

Golden list for safe driving

• The car has gotten taller: Forget low enclosed shopping mall parking lots, watch out for tree branches, and be very careful when entering the ship’s garage.

• Speed limit: With a roof box, the car is more affected by side winds. Manufacturers set the maximum safe limit at 130 km/h.

• Secure the items inside: Always use the fastening straps included inside the roof box to stabilize the bags. If you don’t secure them, in a sudden brake they will all move forward, altering the car’s road behavior.

• Take it off after the trip: When you get back, don’t leave it on the roof. It creates drag and you’ll waste fuel unnecessarily on your daily drives. If you don’t have space at home or in the garage to store it, you can also consider a fabric - foldable roof box that folds up and fits in a closet.