What’s the biggest roof box that will fit my car?

Find the roof boxes that will fit

With your roof bars fitted according to their instructions and your boot fully open, enter the distance from the middle of the front bar to the nearest point of the open boot, in cm.

Results check boot clearance using our verified figures. Roof load limits and mounting compatibility must also be checked. “Largest” means highest capacity in litres.

Largest roof box by available boot clearance

Use your measured distance to find the largest-capacity option whose required clearance is below it. This comparison uses our listed boxes with verified clearance figures. Your measurement must be greater than the figure in the first column; roof load and mounting requirements must also be met.

With 130 cm available, for example, the largest listed option is the 450L Force 3 L. With 140 cm, it is the 590L Motion 3 XXL.

What determines the biggest roof box you can fit?

• Boot clearance: the box must leave space for your boot to open. Your measurement must exceed the exact model’s published requirement.
• Roof-bar compatibility: check the permitted bar spacing, clamp compatibility and fitting positions in the rack and box instructions.
• Roof load: roof bars, empty box and luggage together must remain within your vehicle’s roof load limit. The rack and box limits also apply.
• Dimensions: check length, width and height as well as litres, particularly if you carry bikes alongside the box or use a low garage.

For example, a hypothetical 75 kg vehicle roof limit with 5 kg of bars and a 20 kg empty box leaves 50 kg for luggage, provided the rack and box also permit that load.

Roof box size questions

What size roof box will fit my car?

Start with your front-bar-to-boot measurement, then check the exact box’s mounting requirements and your vehicle’s roof load limit. Our finder compares boot clearance; it is not a complete vehicle compatibility check.

Can I put a large roof box on a small car?

Possibly. A small car does not automatically need the smallest box. The roof-bar installation, boot clearance, roof load limit and box dimensions determine which models are suitable.

Will a 500L or 600L roof box fit my car?

Litres describe storage volume, not fit. In this comparison, the 500L Thule Force 3 XL requires more than 134.7 cm of front-bar-to-boot clearance. The 590L Motion 3 XXL requires more than 139.1 cm. Both still need compatible bars and a suitable roof load allowance.

Is the longest roof box always the biggest?

No. A long, low ski box can have less capacity than a shorter, taller box. Compare litres for storage volume and internal dimensions for long or bulky items.

Does a bigger roof box carry more weight?

Not necessarily. A larger volume does not increase the vehicle’s permitted roof load. A heavier empty box also leaves less of that allowance for luggage.

Can I move my roof bars to make a larger box fit?

Only where your vehicle and roof-rack fitting instructions allow it. Do not move bars outside their approved positions to gain boot clearance.

What if my measurement equals the clearance figure?

The finder requires your measurement to be greater than the listed figure. For a box requiring more than 132.4 cm, a measurement of exactly 132.4 cm is not counted as a match.

What if my roof box is not listed?

If a roof box is not listed, we do not have a verified boot-clearance measurement and are unable to confirm whether it will fit your car.

How this roof box size guide works

Prepared by Roof Boxed, a Thule retailer with a showroom in Castle Combe, Wiltshire. The finder compares your measurement with model-specific clearance figures and ranks matches by capacity in litres. “Largest” means the highest capacity among the models included, not every roof box available on the market.

Clearance values are stored in millimetres and displayed in centimetres without rounding away the required precision. Product prices and availability load from our current listings; the comparison data must be reviewed when model specifications change.

Manufacturer references

• Thule Motion 3 XL: Thule manufacturer specifications — front-bar-to-boot clearance must exceed 132.4 cm.
• Thule Motion 3 XXL: Thule manufacturer specifications — front-bar-to-boot clearance must exceed 139.1 cm.
• Thule Force 3 M - Medium 400L: Thule manufacturer specifications — front-bar-to-boot clearance must exceed 114.9 cm.
• Thule Force 3 L - Large 450L: Thule manufacturer specifications — front-bar-to-boot clearance must exceed 128.5 cm.
• Thule Force 3 XL - 500L: Thule manufacturer specifications — front-bar-to-boot clearance must exceed 134.7 cm.

Check the exact model’s current fitting instructions before installation.

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