The roof box size checker
What size roof box do I need?
Tell us how many cases and awkward extras you are carrying. Get a quick capacity estimate before you buy or hire a roof box.
01
Capacity is the first filter
Suitcase count gives a more useful starting point than box length alone.
02
Leave breathing room
A box should not be packed solid; soft bags and odd shapes need spare space.
03
Check the car separately
Roof bars, maximum roof load and hatch clearance still decide what is safe.
An estimate, not a safety approval
This estimates luggage volume only. Before buying or hiring, check the roof box's internal dimensions, your roof bars, the car manufacturer's maximum roof load and the box's maximum load. Heavy items belong in the boot whenever possible.
Read UK roof box guidance ↗