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Roof boxes

Choose a roof box around luggage size, roof load, mounting and hatch clearance. Compare shapes, access, Amazon options and practical buying guides.

Soft travel bags measured and laid out for a weekend away

The short answer

The best box is the one that takes your actual bags, stays within the load limits and leaves the hatch usable. Buying the biggest one you can find is rarely a helpful starting point.

Compare the shortlist →Check roof load

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Three very different boxes

See the full comparison →
Compact luggage03

VonHaus 320L car roof box

VOLUME320LPLAN EMPTY11.5kgLENGTH132cm

A shorter, lighter shell for compact bags and occasional trips. Single-side opening; mounting requirements need confirmation.

View on Amazon UK ↗Read the full comparison ↓

Find the box around your limiting measurement

Start with the load that cannot sensibly travel in the boot, then establish why it needs roof space. A camping load may run out of usable length; winter clothing may run out of volume; a low vehicle allowance may run out of weight first. Those are different problems, so a larger litre figure is not always the next step.

For example, a long narrow tent bag can make internal length decisive even when a shorter box has similar nominal capacity. A tall rigid case can fail beneath the lid of either box. Trial-pack the awkward item first, then measure the room left for everything else; the soft-bag versus suitcase comparison explains where flexible luggage helps and where it does not.

Decide on shape before capacity

Litres describe volume, but not whether a long bag will fit through the opening or sit below the tapered lid. Check the internal dimensions, including width and height, against the luggage you plan to take. A short, wider box can be useful for soft bags; a long, narrow box may suit longer equipment or a shared roof layout.

Short and wide

Useful for compact soft bags. Shorter shells need less off-car storage length.

Long and narrow

May suit longer equipment, or leave bar width for another carrier when the full layout allows.

Measure awkward items in their packed form. Ski length, tent-bag length and suitcase height can rule out a box even when the volume sounds ample. Leave room for the mounts and internal straps as well as the lid.

Compare the practical consequences in our worked Force 3 versus Motion 3 size-pair analysis and standard XL versus XL Low calculation. Each shows the source figures and calculated differences, while the main shortlist compares luggage allowance under the same roof limits.

Think about loading access

Two-sided opening

Load from whichever side of the car is convenient — useful when the driveway and destination car park differ.

Single-side opening

May be enough for occasional trips. Think about where you park and whether you can reach every mounting point.

Our single-side versus dual-side comparison works through reach and parking position. For attachment hardware, compare U-bolts with quick clamps against the actual bar profile and mounting range.

A quick-mount system can make attachment more convenient. It still has to match the crossbar dimensions and permitted spacing. Check those instructions before treating the mounting system as a reason to buy.

What else needs to fit?

  • The hatch: compare the model's clearance method and figure with measurements from your fitted bars. Only move bars where the rack instructions permit.
  • The roof allowance: include bars, feet, fitting kit, the empty box and other equipment before calculating luggage weight.
  • The journey: measure the assembled height and check restrictions for parking, ferries and accommodation.
  • Your home: a long box needs somewhere to live when it is off the car.

A useful order for buying

  1. STEP 01Confirm the car’s roof limit
  2. STEP 02Choose the approved complete rack
  3. STEP 03Measure usable bar and hatch space
  4. STEP 04Shortlist a box around your luggage
  5. STEP 05Check the full installation instructions

Work through fit and roof load →

Hard box or roof bag?

A hard box provides a shaped shell and usually a lock, but takes up storage space at home. A soft roof bag can pack down between trips, though its attachment method, weather protection and permitted support differ by product. Do not assume that a bag advertised for use without bars is suitable for your car's roof, door seals or glass panels.

Start with the carrying system your car supports, then compare storage and access. If off-car storage is the main obstacle, plan a storage method before ruling out a box.

Where to check the details

Our roof-box guide compares the three exact variants and records their manufacturer dimensions and instructions. Use the model’s manufacturer instructions for mounting details; your own vehicle handbook remains the source for its roof-load allowance. Thule's packing and load guidance explains why rack and empty-box weights matter. VonHaus's 320L specification provides that particular model's dimensions and loading information; it is not a mounting specification for another box.

Comparing the Thule ranges? The Force 3 versus Motion 3 guide compares equivalent sizes. Our three-box shortlist deliberately uses different shapes for different needs, so compare its L Sport and XL examples around their different carrying tasks.

Explore the detailed roof-box guides

Choose a page around the decision you are making. Start with size and packed dimensions, then check the access and mounting requirements before comparing the cost of ownership.

For an upgrade, check replacing the box while retaining your bars. Before purchasing, compare warranty terms, spare parts and the claim process alongside fit and usable capacity.

Size, shape and carrying method

Start with the packed luggage and the constraint you need to solve.

Access, attachment and model comparisons

Compare the actual opening and mounts after establishing the usable space.

Used boxes, occasional use and upgrades

Include condition, storage, parts and ownership costs in the purchase decision.

Frequently asked questions

What size roof box should I choose?

Start with the actual packed luggage and the usable interior shape. Check long items, rigid corners, mounts and the sloping lid before comparing litres. Then verify vehicle fit, roof allowance, hatch clearance and storage space.

Are the roof boxes in the shortlist suitable for every car?

No. Each is a specific size and model with its own mounting range and restrictions. A suitable car needs an approved complete rack, compatible box attachment, adequate clearance and enough load allowance for the empty equipment and luggage.

Should I choose a narrow box or a low-profile box?

A narrow box may help a measured shared-roof layout; a low-profile box may reduce fitted height while losing usable interior height. Choose around the problem you need to solve and measure the complete approved arrangement.

Do dual-side opening and quick clamps prove that a box fits?

No. Those features affect access and installation within the specified system. Bar geometry, spacing, underside clearance, the vehicle fit and all load limits still need independent checks.