Choosing the right roof box size
A roof box is one of the easiest ways to add extra storage to your vehicle, especially if you’re carrying bulky but lightweight gear. They’re useful for ski trips, family holidays, camping gear, prams, sleeping bags, sports gear and all the bits that quickly fill the boot.
The main thing is choosing a box that suits your vehicle and the gear you actually carry. A bigger roof box gives you more space, but it also needs to work with your roof racks, vehicle length, hatch clearance and roof load rating.
What are you planning to carry?
Start with the gear you’ll use the box for most often. Roof boxes are best for lighter, bulky items like jackets, sleeping bags, duffel bags, ski gear, camp chairs and soft luggage.
Quick roof box size guide
If you just want a simple starting point, use the guide below. The right roof box still depends on your vehicle, roof rack position, hatch clearance and what you are carrying, but this gives you a good place to start.
| Roof box size | Best suited to | Common uses |
|---|---|---|
| Small / Sport | Compact cars, hatchbacks and smaller SUVs | Weekend bags, jackets, light travel gear, extra boot space |
| Medium | Wagons, compact SUVs and mid-size SUVs | Family trips, soft luggage, camping gear, snow gear |
| Large | Mid-size SUVs, large wagons and family vehicles | Longer trips, prams, soft bags, skis, snowboards and bulky gear |
| XL / XXL | Large SUVs, utes, vans and bigger family vehicles | Ski trips, camping, longer holidays and maximum storage |
| Low-profile / alpine | Larger vehicles with enough roof length | Skis, snowboards and lower-height setups |
For ski and snowboard gear, internal length matters more than litres. You can also browse roof boxes by max internal length or view our Ski and Snowboard Roof Boxes.
Match the roof box to your vehicle
Before choosing a roof box, think about the size and shape of your vehicle. A Compact Hatchback, Wagon, SUV or Ute can all suit different box sizes.
It’s also worth checking the distance between your roof racks and how the box will sit on the vehicle. All Thule and Rhino-Rack roof boxes we stock are compatible with the roof racks we sell, but the right size still depends on your vehicle, rack position and what you want to carry.
Rear hatch clearance is another big one. If your tailgate opens upward, a longer roof box may sit too far back and touch the hatch when it opens. A 500L XL box on a small car might technically fit the bars, but it may not be the best match in real life.
Not sure what size will work? Check out our Roof Box Hatch Clearance Guide to help avoid surprises before you order.
How much roof box space do you need?
Roof box sizes are usually listed in litres, but litres only tell part of the story. Shape, internal length and usable width matter too.
As a rough guide, compact boxes are handy for day-to-day gear and smaller vehicles. Medium and Large boxes suit family trips, soft luggage and camping gear. XL, XXL and low-profile alpine-style boxes are better when you need extra length for skis, snowboards or bulky winter gear.
You can also filter our roof boxes by Max Internal Length and Load Capacity on our Roof Box Collection.
Pack your roof box properly
Roof boxes are best used for lighter gear, not heavy items. Before loading up, check your vehicle roof load rating, roof rack load rating and the roof box load limit. The lowest rating in that setup is the one that matters.
When packing, keep the heaviest items near the centre of the box, around the area between your roof racks. Spread lighter gear toward the front and rear, and strap the load down inside the box so it can’t shift while driving.
Soft bags make roof boxes much easier to pack than hard suitcases. The Thule GoPack Duffel Set is a good option if you want bags that fit neatly into most roof boxes and make unpacking quicker when you arrive.
Don’t forget the roof racks
A roof box needs roof racks to mount to. If you already have roof racks, check the bar shape, usable width and load rating before choosing a box.
If you still need roof racks, start with a vehicle-specific kit so the bars are matched to your make, model, year and roof type. You can shop roof racks here, or get in touch if you’re unsure what fits your vehicle.
