If there's one guarantee in life, it's that whatever luggage or sporting equipment you're looking to transport, there's already a perfectly designed roof box ready to help store it.
But if you've never bought a roof box before, you are likely to be overwhelmed by the vast number of boxes on offer.
To help you make the right choice for your vehicle and individual needs, we've put together this complete guide to buying a roof box. Taking you step-by-step through the world of roof boxes, you will be ready to make a confident purchase choice in no time.
What is a roof box?
A roof box is a large luggage compartment that fits to the roof bars on the top of your vehicle and allows you to easily carry up to 50 kg of additional luggage.
The different types of roof boxes
There are three different types of roof boxes available. Each differs in length, width and height to fit a range of different car roofs and load capacities.
Narrow boxes
Up to 60 cm in width, these roof boxes are usually utilised by people who want to leave space on the roof for a kayak or up to three bike carriers.
Medium-width boxes
Up to 75 cm in width, the medium-width roof box is usually installed when the user wants to leave space for one bike. These boxes are also popular due to being significantly easier to lift and move when compared to a full-width box.
Full-width boxes
Up to 95 cm in width, a large roof box is one of the most popular options for families. Allowing you to maximise your load capacity, these boxes offer dual-sided opening and will fit the full length of the roof bars. The downside of this rooftop box is that they are quite difficult to manoeuvre due to their bulky weight and size.
What size roof box do I need?
If you are struggling to decide on the right roof box for your needs, check out the roof box size guide below. Offering a clear sizing system, you can easily determine the right box for the type of luggage you carry most.
| Roof Box | Gear | Additional Carry |
| 320 L Narrow Box |
Groceries, Household Items, Carry-On Luggage |
2-3 Bikes, Kayak |
| 400 L Mid-Width Box |
Outdoor Equipment, Baby Gear,
Luggage |
1-2 Bikes |
| 460 L Full-Width Box | Oversized Luggage | None |
Do I need roof bars to fit a roof box?
Yes, you will always need a set of roof bars to fit a box. To fit a roof box, you will need both a set of roof bars that run down the length of your vehicle and also a set of roof bars that run across the width of your vehicle from one side to the other.
Should I buy steel or aluminium roof bars?
Steel roof bars are the traditional bars of choice as they are cheaper to produce. However, there are many problems that you are likely to encounter with steel roof racks. Firstly, they produce a large amount of drag. This can cause you to waste a lot of fuel and contribute towards a loud, annoying humming sound. Secondly, modern roof boxes and bike carriers have u-bolts or claw grippers which offer universal fitting. Unfortunately, steel bars are often designed in a way where you will need roof bar specific equipment. The equipment can often be quite expensive.
Our recommendation is to pick aluminium roof bars. They may be slightly more expensive, but they offer a plethora of benefits. Firstly, they are lighter so you can carry more luggage. And secondly, they are low drag which saves both your fuel and eardrums.
Best Narrow Box
Offering 320 litres of load capacity, the MWAY Venom 320 has to be your narrow box of choice. Super easy to fit, this box has multiple fixing holes along the bottom of the roof box so you can fit to any length vehicle.
Search prices on the MWAY Venom 320 L here
Best Mid-Width Box
For a mid-width box with some serious load capacity, check out the MWAY Venom 400. Testing shows that this box offers the least drag while offering a massive 400 litres of loading space. Perfect for carrying all your normal size luggage, kids toys and football equipment.
Search prices on the MWAY Venom 400 L here
Best Large-Width Box
For a streamlined roof box that maximises your carrying capacity at a low price, check out the MWAY Venon 460. Offering perfect aerodynamics, a central locking system and twin dynamic spring struts, this roof box is stable, secure and easy to use. The perfect all-rounder for the family looking to carry lots of extra luggage.
Search prices on the MWAY venon 460 L here
Can I fit a roof box myself?
Yes, it could not be easier.
All roof boxes sold by Witter Towbars have been tested for single-person fitting and removal.
Don't believe us? Watch our installation video below
Can fitting a roof box affect my insurance?
It mostly depends on the insurance provider but, yes, fitting a roof box can potentially be classified as a car modification. It is essential that you notify your insurance provider about this change to your vehicle. Car modifications can affect how your insurance premium is calculated and, if you don't tell your insurance provider, they may use the modification to invalidate your policy in the event of an insurance claim.
Note: Always notify your insurance provider when making modifications to your car.
Can you fit suitcases in a roof box?
It will largely depend on the type and size of roof box you have purchased and the size and type of suitcase you own. The MWAY Venom 460 L we recommended above, will fit almost all normal size suitcases. It will also generally fit most abnormal size suitcases, but please check the product measurements first.
Can you fit a roof box to any car?
This will largely depend on the type of roof box you have purchased. Some brands will allow universal fittings while other roof boxes will only fit to specific roof bars. The three options we have mentioned by MWAY offer universal fitting as they have universal fixing holes along the bottom of the roof box. This allows you to fit the roof box to any length vehicle.
