A rooftop cargo bag is a soft, zippered carrier that straps to a roof rack or, on a car with no rack, to the door frames. All four bags here are sold for use with or without a rack, so the real differences are size, how each maker rates it against water, and what comes in the box. RoofPax 19 cu ft has a lifetime warranty on zippers and buckles and comes in several sizes. Mockins 20 Cu Ft is the biggest bag here and ships with a roof mat and a lock. Rightline Gear Sport 3 has a waterproof zipper that needs no flap, and Rightline Gear Range 2 is the shortest bag for smaller roofs.
None of the four product pages gives a fixed weight limit for the bag. RoofPax says the weight its bag can hold depends on your car model and points you to your car maker’s manual, so check that first. Our roof rack load rating guide explains how to find the lowest limit in the chain. If you’d rather have a rigid, lockable shell, compare our rooftop cargo boxes .
All specs come from the RoofPax, Mockins and Rightline Gear product pages (Rightline Gear is sold through Klymit’s store), checked on October 9, 2026. Nobody mounted or loaded these bags for this page.
Quick picks
| Pick | Best for |
|---|---|
| RoofPax 19 cu ft | a long warranty and a choice of sizes |
| Mockins 20 Cu Ft | the most space here, with a roof mat and lock in the box |
| Rightline Gear Sport 3 | wet weather, with a waterproof zipper that needs no flap |
| Rightline Gear Range 2 | shorter roofs, in the shortest bag here |
Compare the specs
| Pick | Volume | Outside L x W x H | Water claim (maker) | Without a rack | In the box |
|---|---|---|---|---|---|
| RoofPax 19 cu ft | 19 cu ft | 47.2 x 35.4 x 19.8 in | Waterproof | 4 door hook straps | Door hook straps, combination lock, storage bag |
| Mockins 20 Cu Ft | 20 cu ft | 50 x 36 x 19 in | Mixed: waterproof (product page), water-resistant (FAQ) | Door hooks | Roof mat, lock, ratchet and buckle straps, storage bag |
| Rightline Gear Sport 3 | 18 cu ft | 48 x 36 x 18 in | 100% waterproof | Car Clips on the door frame weather molding | Straps, Car Clips, set-up guide |
| Rightline Gear Range 2 | 15 cu ft | 40 x 36 x 18 in | Weatherproof | Car Clips on the door frame weather molding | Straps, Car Clips, stuff sack, set-up guide |
1. RoofPax 19 cu ft
Best for: a long warranty and a choice of sizes
The 19 cu ft RoofPax bag measures 47.2 x 35.4 x 19.8 in. It is made from 600D double-coated recycled polyester rather than PVC, with double waterproof zippers and dual-seam construction, and RoofPax lists it as waterproof. The same bag also comes in 15, 23 and 28 cu ft sizes and an expandable 15-19 cu ft version. RoofPax covers zippers and buckles for life and tears and fabric for 5 years.
RoofPax says the bag works with a roof rack, raised side rails, crossbars or no rack at all. On a rack, you strap it to the rack, crossbars or basket. Without one, its 4 patented door hook straps go below the door’s weatherproofing rubber gasket, and RoofPax says to use all four. A combination lock and a storage bag are also in the box.
The trade-off: RoofPax says sliding doors can’t take door hooks, and it recommends a rack, crossbars or other attachment points on sliding-door vehicles
Before ordering, check your door type, and look up your car maker’s roof limit, since RoofPax ties the bag’s capacity to your car model
2. Mockins 20 Cu Ft
Best for: the most space here, with a roof mat and lock in the box
The yellow Mockins 20 cu ft bag (product code MA-155) measures 50 x 36 x 19 in, the most volume of the four bags compared here. It is made from heavy-duty, abrasion-resistant vinyl. The product page calls it 100% waterproof, but Mockins’ roof bag FAQ describes its roof bags as water-resistant and suggests sealed plastic bags inside for heavy rain. Mockins lists universal vehicle fitment: the bag attaches with or without crossbars and side rails, and door hooks add attachment points.
The kit is the most complete on this list. It includes a 40 x 36 in rooftop mat that Mockins says keeps the bag in place and protects the top of your vehicle, plus ratchet and buckle straps, a combination lock and a storage bag.
The trade-off: Mockins publishes no fixed weight limit for this bag (its roof bag FAQ says the limit depends on your vehicle’s roof capacity), and at 50 inches it is the longest bag here
Before ordering, measure the flat part of your roof against the 50 x 36 in footprint
3. Rightline Gear Sport 3
Best for: wet weather, with a waterproof zipper that needs no flap
Sport 3 holds 18 cu ft in a 48 x 36 x 18 in bag. Rightline Gear rates it 100% waterproof, with welded seams and an SZIP waterproof zipper that it says needs no zipper flap. The material is UV-protected PVC Semi-Coated Mesh XT. Rightline says the enclosed front end helps fit your gear to the size of the carrier and prevents overfilling.
Rightline designs it for SUVs and minivans, with or without a roof rack. You run the straps to the rack, or use the included Car Clips to attach them to the door frame weather molding. The box holds the carrier, attachment straps, Car Clips and a set-up guide.
The trade-off: Rightline’s product page lists no weight limit and no lock
Before ordering, measure the flat length of your roof against the 48-inch bag
4. Rightline Gear Range 2
Best for: shorter roofs, in the shortest bag here
Range 2 holds 15 cu ft in a 40 x 36 x 18 in bag, the shortest of the four. Rightline calls the Range 2 weatherproof rather than waterproof, which is the main difference from the Sport 3, and lists welded seams and a urethane-coated zipper. It uses the same UV-protected PVC Semi-Coated Mesh XT and attaches the same way, to a rack or with Car Clips on the door frame weather molding. A stuff sack comes in the box with the straps, Car Clips and set-up guide.
The trade-off: weatherproof is a lower claim than waterproof, and 15 cu ft is the smallest volume here
Before ordering, decide how wet your trips get, and pack anything that must stay dry in its own sealed bag
How to choose a rooftop cargo bag
Find your weight limit first. None of the four product pages lists a fixed maximum load for the bag. RoofPax says the weight its bag can hold depends on your car model and refers you to your car maker’s manual. If you have a roof rack, its rating counts too, and the lowest number wins. Our roof rack load rating guide shows where to find each one.
Rack, rails or bare roof. All four bags attach either way. With a rack, the straps go to the rack; RoofPax also lists crossbars and roof baskets. On a bare roof, RoofPax and Mockins use door hooks, and Rightline uses Car Clips on the door frame weather molding. RoofPax notes that sliding doors can’t take door hooks. If your straps run to crossbars, our strap length guide helps you pick a length.
Waterproof or weatherproof. Each maker words this differently. Rightline rates the Sport 3 100% waterproof and the Range 2 weatherproof. Mockins’ product page calls its bag 100% waterproof, while its roof bag FAQ calls its roof bags water-resistant. RoofPax lists its bag as waterproof but still recommends extra precautions so cargo isn’t damaged by any water that may seep in. Keep electronics and papers in their own sealed bags either way.
Size to your roof, not just your cargo. Compare each bag’s length and width with the flat part of your roof. The bags here run from 40 in long (Range 2) to 50 in (Mockins), and from 15 to 20 cu ft.
Security and storage. RoofPax and Mockins include a combination lock. Rightline’s product pages don’t list one for the Sport 3 or Range 2. RoofPax and Mockins include a storage bag, and Range 2 comes with a stuff sack.
Care between trips. RoofPax says to inspect the seams and openings for wear before each use and to close every zipper fully. To clean its bag, wipe the outside with a damp cloth and mild soap, and let it air dry completely before storing it.
FAQ
Can I use a rooftop cargo bag without a roof rack?
Yes. All four bags here are sold for use with or without a rack. RoofPax and Mockins use door hooks, and Rightline Gear uses Car Clips on the door frame weather molding. RoofPax says sliding doors can’t take door hooks.
How much weight can a rooftop cargo bag hold?
None of these four product pages gives one fixed number. RoofPax ties the figure to your car model and points you to your car maker’s manual, so start there, and stay within your roof rack’s rating if you use one.
Should I get a bag or a hard roof box?
A bag can go on a car with no rack, while every box on our rooftop cargo box shortlist needs crossbars. Each box on that list is a hard shell with a maker load limit. None of the bags here lists a load limit, but RoofPax, Mockins and the Range 2 come with a storage bag or stuff sack for when the bag is empty.
Sources
See Also
If you want to pressure-test this shortlist, read Best Roof Bike Racks: Fork-Mount, Upright and No-Rack Options, Best Rooftop Cargo Boxes: Compare Volume, Load Limit and Hatch Fit, and Best Tailgate Bed Extenders for Keeping Cargo Inside the Truck Bed next.
For more context beyond the main ranking, Receiver Hitch Inspection Points Before Each Trip and Extang Trifecta 2.0 Tonneau Cover Review: Fit, Features, and Trade-Offs add useful comparison detail.