Guides
Are Cargo Boxes Worth It?
Worth it above about three trips a year, if you can store it and you accept the fuel cost. Below that, buy something else.
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A rooftop cargo box is worth it if you will use it roughly three or more times a year, you have somewhere to store it, and you accept a double-digit percentage fuel penalty while it is up there. Under those conditions it is one of the better things you can buy for a family car. Outside them, a cargo bag, a hitch carrier or a rental is the better spend.
The case against is mostly cost, and it is larger than the sticker. A box is a box plus crossbars plus a foot pack plus a fit kit, and on a car with a bare roof the rack can cost as much as the box. Then there is the running cost: Consumer Reports measured a 19% fuel economy loss on a sedan with a rack and rooftop carrier fitted and 13% on an SUV, which is real money over a long trip.
The case for is that nothing else solves the same problem. A full trunk and four people is not fixed by packing better, and a box turns an impossible journey into a comfortable one. Below: the arithmetic to run before buying, the four alternatives and when each wins, then the boxes and the bag worth looking at.
Quick picks
Tap any row to jump to the full write-up below. Scores are our editorial judgment on published specifications — not a star rating, and not a product we claim to have tested.
| # | Product | Best for | Score | Price |
|---|---|---|---|---|
| 1 |  Thule Force 3The mid-tier Thule box in sizes from roughly 300 to 610 liters — enough range that one size fits most families without paying flagship money. | The box to buy if the answer is yes | 8.3 | |
| 2 |  RoofPax Car Roof BagA waterproof soft bag with door-hook straps — works with or without a rack, folds into a cupboard, costs a fraction of a shell. | If the answer is no, buy this instead | 7.8 | |
| 3 |  MaxxHaul 70107A 60 by 20 inch steel basket rated 500 lb on a 2-inch receiver — the load moves into the car's wake, where it costs far less fuel. | If fuel is the objection | 7.9 |
Prices checked October 11, 2026. Product photographs come from Amazon and are refreshed with the prices. Affiliate disclosure.
#1 · The box to buy if the answer is yes
Thule Force 3
The mid-tier Thule box in sizes from roughly 300 to 610 liters — enough range that one size fits most families without paying flagship money.
- Sizes
- Roughly 300 to 610 liters
- Shell
- Hard
- Opening
- Dual side
- Position
- Mid-tier
What works
- Covers most family needs without flagship pricing
- Dual-side opening, which matters every single time you load it
- Thule's mounting and lock ecosystem, which resale value follows
- Sealed, locked and quiet relative to any open carrier
What doesn’t
- Needs crossbars and a fit kit, which can match the box's cost
- Needs real storage space for eleven months of the year
- Carries a double-digit fuel penalty while fitted
Our scoring
8.3overall
#2 · If the answer is no, buy this instead
RoofPax Car Roof Bag
A waterproof soft bag with door-hook straps — works with or without a rack, folds into a cupboard, costs a fraction of a shell.
- Type
- Soft waterproof bag
- Mounting
- Crossbars or door-hook straps
- Storage
- Folds away
- Rack needed
- No
What works
- No rack required, which removes the hidden half of a box's cost
- Stores in a cupboard rather than needing garage space
- A fraction of the price of a shell plus bars
- Nothing left on the car between trips, so no residual fuel penalty
What doesn’t
- No security — fabric and a zip
- Noisier and draggier than a shaped shell when stuffed full
- Door-hook straps can track water into the seals in heavy rain
Our scoring
7.8overall
#3 · If fuel is the objection
MaxxHaul 70107
A 60 by 20 inch steel basket rated 500 lb on a 2-inch receiver — the load moves into the car's wake, where it costs far less fuel.
- Basket
- 60 x 20 inches
- Rated capacity
- 500 lb
- Receiver
- 2-inch
- Position
- In the vehicle's wake
What works
- Far smaller aerodynamic penalty than anything on the roof
- Loads at waist height instead of overhead
- Costs a fraction of a box plus bars
- Carries weight a car roof is not rated for
What doesn’t
- Needs a 2-inch receiver, which many cars do not have
- No weather protection and no security
- Does not fold, so the hatch is blocked
Our scoring
7.9overall
The arithmetic to run before you buy
Four numbers, and you can get all of them in five minutes.
| Number | Where it comes from | What it decides |
|---|---|---|
| Trips per year | Be honest about last year, not optimistic about next | Buy, bag or rent |
| Total setup cost | Box plus bars plus foot pack plus fit kit | Whether the shell is the real expense |
| Highway miles per trip | Your usual route | The size of the fuel penalty |
| Storage space | Garage wall, ceiling hoist or nothing | Whether a hard box is practical at all |
Storage is the one that quietly decides it. A hard box is bulky, it does not nest, and it needs to live somewhere dry for most of the year. Owners without a garage overwhelmingly end up wishing they had bought a bag.
The fuel penalty, in numbers
Consumer Reports measured a 19% fuel economy loss on a sedan fitted with a rack and a rooftop carrier, and 13% on an SUV. Crossbars alone — no box — cost almost 11% on that sedan. Those are the honest figures, and the percentage is worst on the most aerodynamic cars.
Three things reduce it: mount the box as far back as the bars allow, choose a low-profile shell, and slow down, because drag rises with the square of speed. The full breakdown, including the empty-rack figure, is in the gas mileage guide.
The structural fix is to take the bars off between trips. Most owners never do, and it is the single largest saving available — it eliminates the empty-rack penalty entirely for the eleven months you are not traveling.
The four alternatives, and when each wins
- Cargo bag. One or two trips a year, no rack, no storage space. Wins on cost and on storage, loses on security and noise. The comparison is in cargo box vs cargo bag.
- Hitch carrier. You have a 2-inch receiver and you care about fuel. Wins decisively on drag and on weight capacity, loses on weather and security. See roof or hitch.
- Roof basket. The load is bulky, dirty or oddly shaped. Cheap, versatile, loud. See box vs basket.
- Renting. One big trip a year and a tight budget. The arithmetic, and where it stops working, is in rent or buy.
The verdict, by household
Worth it: a family of four or more taking two or more long trips a year, with a garage, on a vehicle whose roof limit gives them useful capacity after the bars and box are subtracted. Also worth it for skiers, because nothing else carries skis as well.
Not worth it: one trip a year; no storage space; a car with a very low published roof limit; or a household that already has a receiver hitch and would be better served by a carrier behind the car.
The middle case — two trips a year, some storage — is genuinely a judgment call, and the deciding factor is usually whether you already own crossbars. If you do, a box is a much smaller purchase than it looks. If you do not, price the whole setup before you decide.
Common questions
Are rooftop cargo boxes worth the money?
How much fuel economy does a cargo box cost?
Is a cargo box or a hitch carrier better value?
Do cargo boxes hold their value?
Sources
Not sure it fits your car?
Our vehicle pages carry the published roof load limit, the roof type by model year, and what actually mounts to it — cited, and honest about what the manufacturer does not publish.
Read next
Roof Rack vs Cargo Box
Why a box needs a rack, what the full setup costs, and when a basket or bag beats both.
Should You Rent or Buy a Cargo Box?
When renting a roof box beats buying one, and the cheaper third option in between.
Cargo Box vs Cargo Bag
Soft bag or hard shell: cost, storage and no-rack flexibility against noise, security and weather.
The Best Cargo Box for an SUV
Hard-shell boxes for SUVs, ranked — plus the weight arithmetic that decides your size before volume does.