What is the best roof box for a family with children?
September 9, 2026
The best roof box for a family with children is a spacious model of at least 400 liters, with a double-sided opening, TÜV certification, and a reliable mounting system. For most families with young children, a roof box between 400 and 530 liters is the ideal choice: large enough for suitcases, buggy parts, and ski gear, without making the car feel unstable on the highway. Below, we answer the most frequently asked questions about choosing the right one. roof box for your car.
How many liters do you need for a family with children?
For a family with two children, a roof box of at least 400 liters is recommended. If you are going to the South of France or the Alps for winter sports, 500 liters or more is sensible. A rule of thumb: count on about 100 liters per person as basic needs, plus extra space for bulky items such as skis, a stroller, or beach chairs.
A 300-liter roof box, like our Hapro Roady, is fine for a couple or a family with very light luggage. But as soon as children come along, the stuff fills up incredibly fast. Think of sleeping bags, toy boxes, rain suits, and ski boots. The Hapro Traxer in the 530-liter variant is the sweet spot for many families: spacious enough for a full family vacation, but compact enough to remain aerodynamic.
Also pay attention to the internal dimensions. A 530-liter suitcase with a low, wide shape fits different items than a narrow, tall suitcase of the same capacity. Check whether skis or a foldable buggy actually fit before making a choice.
Does a roof box fit on every car and roof rack?
No, a roof box does not automatically fit every car or roof rack. The box must be compatible with the type of roof rack mounted on your car, and the width of the box must not exceed the width of your roof. Always check your car's maximum roof load on your vehicle registration certificate.
Most modern roof boxes are suitable for roof racks with a bar width of 60 to 110 cm, but this varies by model. With us, you can quickly check which roof box and roof rack fit your specific car via the online configurator on the Hapro website. This way, you avoid buying a box that doesn't fit or exceeds the maximum roof load.
Also take the height of the roof box into account. A high box can cause problems in a parking garage or on a car ferry. Check the total ride height of your car, including the roof box, before you leave.
How fast are you allowed to drive with a roof box?
With a roof box on your car, you are allowed to drive at the applicable speed limit in the Netherlands and most European countries, provided the box is mounted correctly and the maximum roof load is not exceeded. The manufacturer usually specifies a maximum recommended speed, often 130 km/h, but always consult the manual for your specific model.
In practice, it is wise to be extra alert regarding wind sensitivity at high speeds. A full roof box raises the car's center of gravity and increases the frontal area, which affects stability and fuel consumption. Driving at 110 to 120 km/h is more comfortable and economical than driving at full throttle on the Autobahn.
A aero dynamically tested model makes a noticeable difference here. Our Hapro roof boxes have been thoroughly tested for wind and vibrations, ensuring you drive smoothly and quietly, even on the highway, without unwanted noise or instability.
What is the difference between a cheap and an expensive roof box?
The biggest difference between a cheap and a more expensive roof box lies in material thickness, locking mechanism, aerodynamics, and mounting system. Cheaper models are often made of thinner ABS plastic, have a simpler lock, and can produce more noise at high speeds. More expensive models are more robust, quieter, and user-friendly over the long term.
What you get with a cheaper model
A budget roof box does what it is supposed to do: transport belongings from A to B. However, installation is sometimes more cumbersome, the closure less smooth, and the lifespan shorter. After a few years of intensive use, cheaper models may discolour, shrink, or close less effectively due to weather conditions.
What you get with a high-quality model
A mid-range or premiumsegment roof box offers thicker walls, better rain sealing, a smooth double-sided locking system, and easier mounting. With the Hapro, we use the patented Premium-Fit mounting system, which allows you to mount and dismount the box without tools. For a family that uses the box several times a year, a high-quality model pays for itself in terms of convenience and durability.
Which roof box is safest for the highway?
The safest roof boxes for highway use are models with TÜV certification, tested for crash resistance, stability, vibrations, water, and wind. A TÜV seal of approval means that the box has been independently tested for safety and reliability under driving conditions. Always choose a certified model if you regularly drive long distances.
In addition to certification, the mounting system plays a crucial role. A case that is not properly locked to the roof rack can shift during sudden maneuvers or strong winds. Before every trip, check that the case is securely fastened and that the lock is properly closed.
Aerodynamic design also contributes to safety. A well-streamlined roof box behaves more stably at high speeds and produces less wind noise, which improves driving concentration. All roof boxes in our range are dynamically tested and TÜV-certified, so you can take to the motorway with confidence.
How do you correctly attach a roof box to your car?
To correctly attach a roof box, place the box on the roof racks, connect the clamps or mounting system to the racks, and check the lock until it is securely fastened. Always mount the box with the opening facing the side that is most practical for your situation, usually the passenger side.
Always follow these steps during assembly:
- Check if the roof racks are securely and correctly mounted on your car.
- Lift the case onto the roof and position it centrally above the roof racks.
- Attach the clamps or the mounting system to the roof rack tubes.
- Tighten the locks until you feel resistance.
- Shake the case vigorously back and forth to check if it moves.
- After driving the first 10 to 15 kilometers, check if everything is still securely fastened.
Never exceed your car's maximum roof load. You can find this on your vehicle registration certificate or owner's manual. The weight of the roof racks themselves also counts. Do you have questions about installation or would you like to know which model best suits your car? Contact us and we are happy to assist you further. Or view our full range directly at vdlhapro.com.
Frequently Asked Questions
Can I leave my roof box on the car all year round?
Technically, that is possible, but it is not recommended. A roof box that remains permanently on the car increases fuel consumption year-round, and exposure to UV radiation, frost, and heat can damage the material over time. It is wiser to remove the box when you do not need it and store it in a dry place out of the sun — this way, it will last considerably longer.
How much extra fuel do I use with a roof box on the car?
An empty roof box increases fuel consumption by an average of 10 to 15 percent on the highway due to extra air resistance. With a full box, this can rise to 20 percent or more, depending on driving speed, box model, and vehicle type. A dynamically shaped model like the Hapro Traxer noticeably limits this effect compared to a less aerodynamic box — another reason not to blindly go for the cheapest option.
What is the best way to pack items in a roof box for a family vacation?
Place heavy and compact items — such as ski boots or closed suitcases — at the bottom and as far forward as possible (towards the windshield) to keep the center of gravity low and central. Fill in light but bulky items such as sleeping bags, rain suits, and beach chairs afterwards. Use compression bags for soft luggage to maximize available space, and ensure nothing can slide loose by packing items tightly together or securing them with a luggage net.
What do I do if my roof box starts squeaking or vibrating while driving?
Squeaking or vibrating is usually caused by slight play between the box and the roof racks, or by air flowing past the seal. First, check that all mounting clamps are properly tightened and shake the box vigorously back and forth again. If the noise persists, check the rubber seal around the box for cracks or dirt — a clean, intact seal ensures a better closure and less wind noise. If the problems persist, you can contact the manufacturer for a replacement sealing strip.
Can I take a roof box through an automatic car wash?
No, that is strongly advised against. The brushes and high water pressure in an automatic car wash can damage the seal, force the locks, and in the worst case, push the box off the roof racks. Clean your roof box by hand with lukewarm water and a soft sponge. A mild soap or plastic cleaner keeps the material in good condition; never use harsh solvents or high-pressure cleaners.
Is a roof box also suitable for transporting skis, and how do I know if my skis will fit?
Many roof boxes are suitable for skis, but the internal length is the determining factor. Check the inside length of the box and compare it to the length of your skis, including bindings — for adult skis, you typically need at least 185 to 210 cm. Some models, such as the Hapro Traxer 530, offer specific dimensions tailored to this. Unsure? Check the product specifications or use the configurator on the Hapro website to be sure that your skis will actually fit.
What should I check before every long trip with a roof box?
Always perform a brief safety inspection before departure: check that the roof box is securely fastened to the roof racks without play, that the lock is fully closed and locked on both sides, that the rubber seal all around is intact, and that the contents are evenly distributed without protruding objects obstructing the closure. Then drive gently for the first 10 to 15 kilometers and stop briefly to check again that all fastenings are still secure — this is certainly a good habit after loading heavy luggage.