A large roof cargo box can free up cabin space for luggage, camping gear, or winter equipment, but capacity is only part of the decision. You also need to check your roof rack’s fit, your vehicle’s roof-load limit, and how easily you can reach the box. These five options range from a roomy 14-cubic-foot carrier to an 18-cubic-foot Thule model, with different mounting systems and access styles.
Quick Comparison
| Roof Cargo Box | Stated Capacity | Load Limit | Access | Notable Fit or Mounting Details |
|---|---|---|---|---|
| Maxsa Innovations Rooftop Cargo Box | 11.5, 13.5, or 14 cu. ft. stated | Up to 135 lb | Dual-side | Universal-fit claim; check roof rack specifications |
| Thule Motion 3 XL | 18 cu. ft. | 165 lb | One-hand lid access | PowerClick mount; select Thule racks and available adapters |
| SportRack Horizon 2 L | 16 cu. ft. | 110 lb | Passenger side | U-bolt kit; fits SportRack, square, round, and most factory racks |
| Thule Pulse 2 M | 14 cu. ft. / 400 L | 75 kg | Dual-side | Tool-free mounting system with torque indicator |
| Goplus Hard-Shell Cargo Carrier | 14 cu. ft. | 165 lb | Dual-side | Crossbar size limits; four quick-connect anchors |
Capacity and load limits are listed as provided for each product. Always check the box, rack, and vehicle limits before loading; the lowest applicable limit governs.
Our Picks: Best Roof Cargo Boxes With Large Capacity reviews
Maxsa Innovations: A Dual-Side 14-Cubic-Foot Option
This hard-shell carrier is described as having ABS construction, a load limit of up to 135 pounds, and access from either side of the vehicle. Dual-side access can be useful when a parking spot or garage wall blocks one side, while the included keys and locking mechanism are intended to secure the lid.
One detail to check carefully is capacity: the product description lists 11.5, 13.5, and 14 cubic feet, while the title specifies 14. Confirm the exact version and dimensions before ordering rather than assuming every listing variation has the same space. The “universal fit” wording is also not a substitute for checking your rack’s dimensions and mounting points.
This is a practical candidate if you want a hard shell with two-sided access and a stated load limit above some smaller boxes. It does not offer the most storage here, and the inconsistent capacity information makes pre-purchase verification especially important.
Pros:
- Dual-side opening for access from either side
- ABS construction and a stated one-year warranty
- Up to 135-pound load limit
Cons:
- Capacity is listed as several different figures
- Rack compatibility should be confirmed before purchase
Verdict: Consider this box if dual-side access matters and you can verify the exact capacity and rack fit for the version being sold.
Thule Motion 3 XL: The Most Listed Storage Space
With 18 cubic feet of stated capacity, the Motion 3 XL is the largest option in this group by volume. Its listed 165-pound load limit is also the highest here, but your vehicle and roof rack may have lower limits. Thule’s description gives external dimensions of 84.7 × 35 × 17 inches and internal dimensions of 80 × 29 × 15 inches, so check roof space and cargo dimensions before choosing it.
The PowerClick quick-mount system has an integrated torque indicator that clicks when properly mounted. The lid is designed for one-hand opening, and the SlideLock system separates locking from opening and indicates when the box is securely closed. The box is described as fitting select Thule rack systems, with adapters available, so compatibility is not universal.
Its long shape is a useful match for winter gear: the listed capacity accommodates five to seven pairs of skis up to 200 cm or three to five snowboards. The trade-off is its substantial footprint. Measure your roof and check trunk clearance, especially if your vehicle has a short roof or a rear hatch that opens high.
Pros:
- Largest stated capacity in this comparison at 18 cubic feet
- 165-pound stated load limit
- PowerClick mounting system with torque indicator
- Listed space for skis or snowboards
Cons:
- Long dimensions may not suit every vehicle roof
- Compatibility is limited to select Thule racks or suitable adapters
Verdict: Choose the Motion 3 XL if you need the most listed volume, particularly for longer winter gear, and have a compatible rack and enough roof space.
SportRack Horizon 2 L: A 16-Cubic-Foot Box with Passenger-Side Access
The Horizon 2 L offers 16 cubic feet of storage and a 110-pound load limit. That gives it more stated volume than the 14-cubic-foot choices, though its load limit is lower than those of several other boxes in this comparison. Passenger-side access can be convenient when you usually park beside a curb or want to load from one consistent side.
SportRack lists compatibility with its own rack systems, square bars, round bars, and most factory racks. Installation uses the included U-bolt attachment kit, and the central locking system is designed so the key can only be removed when all locking points are closed. Check the exact rack fit and mounting clearances before buying.
This box is a straightforward choice for people who prioritize extra volume and do not need dual-side access. Its listed availability may change, so confirm that it can be ordered before planning around it.
Pros:
- 16 cubic feet of stated storage
- Passenger-side opening
- Fits several common rack styles, according to the product details
- Central locking system and included U-bolt kit
Cons:
- 110-pound load limit is lower than several alternatives here
- Single-side access is less flexible than dual-side designs
Verdict: The Horizon 2 L is worth considering if you want 16 cubic feet and passenger-side loading, provided its availability and rack compatibility work for you.
Thule Pulse 2 M: A 14-Cubic-Foot Box with Dual-Side Access
The Pulse 2 M has 14 cubic feet, or 400 liters, of stated cargo space and a 75-kilogram load capacity. It opens from either side, which can make loading easier when access is limited on one side of the vehicle. The product description also notes full trunk access with minimal risk of contact because of its forward position on the roof.
Its tool-free mounting system includes a torque indicator that clicks when the box is safely attached. Thule describes the shell as ASA-ABS plastic designed to resist sun, scratches, and weather. These features make it a practical option for routine trips, but the stated 75-kilogram box limit does not override a lower vehicle or rack limit.
Compared with the Motion 3 XL, the Pulse 2 M offers less capacity and a lower stated load limit, but it has a more moderate 14-cubic-foot size. Check the product’s current availability and confirm that the mounting system suits your rack before ordering.
Pros:
- Dual-side access
- 14 cubic feet of stated storage
- Tool-free mounting with a torque indicator
- Designed to allow full trunk access
Cons:
- Lower stated load capacity than several other options here
- Availability may vary
Verdict: Choose the Pulse 2 M if a mid-size 14-cubic-foot box with dual-side access and a tool-free mounting system fits your rack and load needs.
Goplus Hard-Shell Carrier: Dual-Side Access and a 165-Pound Limit
The Goplus carrier provides 14 cubic feet of storage and lists a 165-pound load capacity. It has a hard ABS and PC shell, metal lid stiffeners, and dual-side opening. Four quick-connect anchors are included for installation, and the description specifies a double-lock design.
Rack measurements matter with this model. The product details specify compatibility with racks 17 to 22.8 inches wide, with crossbars less than 3.1 inches wide and less than 1 inch thick. It is described as suitable for round, square, factory, and most aerodynamic bars, but only if those dimensions match. The instructions also say not to open both sides at the same time.
Its load limit is higher than some 14-cubic-foot alternatives, but that does not mean you should load it to that figure without checking your vehicle and rack limits. The listed availability may vary, so confirm stock and fit before making it your trip-planning choice.
Pros:
- 14 cubic feet of stated storage
- 165-pound stated load limit
- Dual-side opening and four quick-connect anchors
- Rack dimensions and crossbar limits are specified
Cons:
- Rack width and crossbar dimensions must meet specific limits
- Instructions say not to open both sides at once
Verdict: The Goplus is a strong option on paper if you want a 14-cubic-foot hard shell with dual-side access, but buy only after measuring your rack and checking all load limits.
How to Choose a Large-Capacity Roof Cargo Box
Match the Box to Your Vehicle’s Roof Load Limit
A box’s stated load capacity is not the only limit to consider. Check your vehicle’s owner information and your roof rack’s instructions for their maximum loads. The box, rack, and vehicle may each have different limits; follow the lowest one. Include the weight of the box itself when calculating the load on the roof.
Measure the Rack and Check Mount Compatibility
Do not rely on a general “universal fit” description alone. Compare your crossbar style, width, thickness, and spacing with the box’s mounting requirements. Some models use a specific quick-mount system or require an adapter, while others list compatibility with certain bar shapes. A fit check can prevent a box from being too wide or impossible to secure properly.
Choose Capacity for the Gear You Carry
More cubic feet can help with bulky luggage, camping gear, or several bags, but the box’s shape matters too. If you carry skis or snowboards, compare their length with the usable interior dimensions. For mixed luggage, think about the size and shape of the items you want to store, not just the capacity number.
Consider Which Side Opens
Dual-side access gives you more flexibility if a wall, another vehicle, or a narrow parking space blocks one side. A passenger-side-only box can be convenient if you usually load from the curb. Before buying, consider your normal parking setup and whether you can safely reach the lid on your vehicle.
Check Hatch Clearance and Overall Dimensions
A long or wide cargo box can affect how your rear hatch opens and how much roof space remains available. Compare the product’s external measurements with your vehicle, rack position, and hatch movement. Forward positioning may help preserve trunk access, but you should still confirm the box will not interfere with your particular vehicle.
Review Mounting and Locking Details
Look for clear instructions about how the box attaches and how you know it is secure. Torque indicators, locking systems, and included keys vary by model. After installation, follow the manufacturer’s directions for closing and locking the lid, and confirm that the box is secured before travel.
Frequently Asked Questions
Which box in this list has the most capacity?
The Thule Motion 3 XL has the most stated storage at 18 cubic feet. Its long external dimensions make it important to check your roof space and rack compatibility first.
Are roof cargo boxes waterproof?
The product details describe weather protection for some boxes, but they do not establish that every model is fully waterproof. Check the manufacturer’s care and weather-resistance information for the specific box, and protect sensitive items as needed.
Can I load a box up to its listed weight limit?
Only if your roof rack and vehicle can also support the load. The lowest stated limit among the box, rack, and vehicle applies. Account for the box’s own weight when checking the roof load.
Does dual-side opening mean both sides can be open at once?
Not necessarily. The Goplus product details specifically say not to open both sides at the same time. Follow the instructions supplied with the model you choose.
Will a roof cargo box fit any car?
No. Most of these options require a roof rack, and compatibility depends on the rack’s bar shape, measurements, and mounting system. Check the box specifications and your vehicle’s roof limits before ordering.
How do I choose between 14, 16, and 18 cubic feet?
Base the choice on the amount and shape of your gear, available roof space, and the load limits of your vehicle and rack. A larger box may fit more items, but it can also have a larger footprint that is not suitable for every vehicle.
Final Recommendation
For the most stated storage, the Thule Motion 3 XL stands out with 18 cubic feet and a listed 165-pound load limit, plus a mounting system with a torque indicator. If you prefer a 14-cubic-foot box with dual-side access, compare the Thule Pulse 2 M, Maxsa Innovations, and Goplus based on rack fit and load limits. The SportRack Horizon 2 L offers a middle ground at 16 cubic feet, with passenger-side access. Whichever you choose, verify the exact product’s availability, dimensions, rack compatibility, and vehicle load limit before buying.