The Best Cargo Boxes for a Subaru Outback

Four criteria, in the order they decide the purchase on this specific car.

1. Empty weight against your generation’s figure. This is first and it is arithmetic, not preference. A 2021 Outback has 150 lb; a 2017 has 176 lb. Subtract bars, subtract the empty box, and what is left is your real packing budget. A box that leaves you 95 lb is a different product from one that leaves you 120 lb even if the brochure volumes match.

2. Length against the roofline, not against the brochure. The Outback’s roof is long, which is good news — but a full-length box can still reach far enough back to interfere with the tailgate when it is fully open. Open the tailgate, look at the arc, then choose a length.

3. Spread, measured. Every box publishes a minimum crossbar spread it needs, center to center. Rail-mount bars slide, so this is yours to set — but the factory integrated bars are a fixed, narrower spread, which is the single most common reason an Outback owner finds their new box will not mount. Our crossbar spread guide shows how to measure it in two minutes.

4. Which side it opens. On a wagon used for family trips, dual-side opening is worth more than it sounds: it decides whether you can unload from the curb or have to walk into traffic.

What we did not rank on is the box’s own load rating. Every box here is rated above what the car allows, so the box’s number is not the constraint — Subaru’s is.

If your Outback is a 2015 or later, it probably has integrated crossbars that stow inside the side rails and swing across the roof. They are a genuinely clever piece of design and they are the reason a lot of cargo box purchases go wrong.

Two problems, both practical. The spread is fixed and narrow — you cannot slide the bars apart to meet a box’s published minimum, so a box that needs a wider spread simply will not mount. And the bars have their own rating, separate from the roof figure, which on the stow-away designs is lower than a dedicated aftermarket bar set.

So the honest sequence for a loaded box on a later Outback is: check the integrated bars’ rating and spread first, and if either one does not clear your intended box, buy dedicated bars before you buy the box. That is not an upsell — it is the order that avoids a return, and our Outback bars page covers which ones.

The flip side: for a light load, a bag or a single bike, the factory bars are fine and free. Not every trip needs new hardware.

The instinct is to buy the biggest box that fits. On this car that is usually the wrong instinct, for two reasons.

The first is the weight budget above: the biggest boxes are the heaviest, and on a 150 lb car the biggest box can leave you with less usable cargo weight than a mid-size one. Volume you cannot fill is not volume.

The second is that an Outback already has a long, usable trunk. The box is there for the bulky-and-light overflow — bedding, coats, camp chairs, a tent — not for the dense items that should travel low. Most families are better served by a mid-size box they can actually lift than by a 610 liter shell they need help with every time.

Two sizing shortcuts. If skis are the reason you are buying, length is the only spec that matters and a long narrow box wins — our ski and snowboard box picks cover the lengths. If the reason is a family of four for a week, volume matters more than shape, and what size cargo box do I need works through the capacity arithmetic properly.

And if you are still deciding between a shell and a bag at all, the cargo box versus cargo bag comparison is the page for it — on a 150 lb Outback the bag’s weight advantage is a stronger argument than it is on most cars.

One Outback does not play by the rules above. The Wilderness trim from 2022 is published at 220 lb (100 kg) dynamic and 700 lb (317 kg) static, which is a different class of allowance entirely — the static figure is there because this is the Outback Subaru rates for a roof-top tent.

If you own one, the box arithmetic stops being tight: a large shell and a full load are comfortably inside the dynamic figure, and the tent question is actually on the table. Our roof-top tent guide explains why the static number is the one tent buyers need and why most vehicles never publish one.

If you do not own one, do not borrow its numbers. This is the single most consequential figure difference inside one model name on this site, and the trim badge is the only thing that distinguishes them at a glance.

Buy the Thule Force 3 in a mid size if you want one box to do everything and you load from both sides of the car.

Buy the Yakima SkyBox NX if skis are the reason, or if you want to keep half the bar free for a kayak or a bike — in which case our J-cradle comparison covers the two carriers that share a bar best.

Buy the INNO Shadow 16 if a garage or a parking structure has a height limit you cannot negotiate with.

Buy the SportRack Vista XL if the box is for two trips a year, and the Thule Outbound bag if your generation’s 150 lb allowance is the thing you keep running into.

And before any of them: check your model year’s figure, check the integrated bars’ spread, and weigh what you plan to pack. On an Outback those three checks matter more than the ranking does. If the load turns out to be heavy rather than bulky, the back of the car is the better place for it — our Outback hitch carrier picks cover that route, including the 1-1/4 inch receiver that rules most carriers out.