If packing for a camping trip, ski day, or beach vacation has ever made your trunk feel like a game of Tetris gone wrong, you’re not alone. Sleeping bags, boots, skis, camp chairs, beach umbrellas – before you know it, there’s no room left for the snacks (or worse, your passengers).
That’s where rooftop cargo boxes swoop in like the superhero of storage. With trusted brands like Thule, you can bring all the gear you need without sacrificing legroom (because let’s face it, nobody wants a cooler riding shotgun).

But here’s the real question: how do you actually choose the right-sized cargo box? Bigger isn’t always better, and smaller isn’t always smarter.

So, let’s break it down.

Step 1 | Think About What You’re Storing

Cargo boxes are best for bulky but lightweight items like:

  • Tents, sleeping bags, and pillows
  • Backpacks, hiking poles, or camp furniture
  • Skis, snowboards, and ski poles (pro tip: keep the boots inside so they’re warm!)
  • Beach gear, kids’ toys, or even strollers

Heavy stuff like coolers and water jugs? Keep those inside the car. Every cargo box has a weight limit, and you don’t want to max it out with a single cooler of root beer.

Step 2 | Double-Check Weight Capacity

Every vehicle has a maximum roof load. Check your owner’s manual for the magic number, then do a little math:
Vehicle’s max load = weight of cargo box + crossbars + towers/feet + your gear.
Staying under that limit means you’ll drive safely, protect your roof, and avoid awkward roadside repacking sessions.

Step 3 | Pick the Right Dimensions

Here’s how to choose the right size cargo box based on your gear:

  • Length: Longer boxes fit skis and snowboards. Shorter ones are fine for tents or summer trips.
  • Width: Wider boxes mean more space, but they may hog room on the rack (goodbye, kayak). Narrow boxes leave space for extra toys up top.
  • Height: Taller boxes = more gear. But remember: garages, parkades, and drive-thrus still need to clear your new roof height.

Step 4 | Match Capacity to Your Crew

Your passenger count usually equals your packing load. Here’s a quick guide:

  • 2 people – 12 cu. ft. / 340 L
  • 3 people – 15 cu. ft. / 425 L
  • 4 people – 18 cu. ft. / 510 L
  • 5 people – 21 cu. ft. / 595 L

If you’re a solo road-tripper, a smaller box with less fuel usage and easier storage capacity is the way to go. Family of five + half the garage? Go big or stay home!

Step 5 | Make Sure It Fits YOUR Vehicle

Don’t skip this step – it’s the one that tends to trip people up. A cargo box should fit your hatch and not look like it belongs on a spaceship.

How to check:

  1. Open your trunk fully.
  2. Measure from the centre of your front crossbar to where the hatch meets the roof.
  3. Compare it with the “front clearance” in the cargo box manual.

If your number is bigger, you’re golden. If not, you’ll need a shorter box or some crossbar adjustments (which we can help with).

Other Things to Consider | Style, Noise & Storage

  • Looks: Black and silver are classics, but size and finish matter too.
  • Fuel efficiency: Bigger boxes = more drag = more gas.
  • Noise: More surface area means more wind noise on the highway.
  • Storage at home: Cargo boxes are awkward – make sure you’ve got the garage space.

Tips for Using Your Cargo Box Like a Pro

  • Keep heavy gear in the car, light gear up top.
  • Distribute weight evenly (60% between crossbars, 40% front/back).
  • Must-have items (snacks, boots, tech) stay inside.
  • Always check overhead clearance before entering garages or drive-thrus.
  • Lock it before driving (sounds obvious, but hey…).
  • Store in a cool, dry place on its base – not on its side.

Top Thule Picks | Cargo Boxes in Calgary

At Calgary Hitch Shop, we stock Thule’s premium ski and cargo boxes, designed with impact-resistant ABS plastic, dual-side opening, and easy PowerClick mounting. Here are a few favourites:

  • Thule Motion XT Large (L)
    Sleek, spacious, and stylish. Perfect for road trips that need extra storage without sacrificing looks.
  • Thule Motion XT Alpine
    Low-profile, aerodynamic, and ideal for winter gear like skis and boards. A top pick for adventurers.
  • Thule Vector Alpine
    The luxury model. High-end design, elegant details, and a premium feel – perfect for Alberta’s winter warriors.

The Bottom Line | How to Choose the Right Size Cargo Box

A rooftop cargo box is one of the easiest ways to upgrade your adventures. The trick? Match the box to your gear, your crew, and your vehicle. Whether you need everyday convenience or all-season adventure storage, there’s a Thule box that’s the perfect fit.

Not sure which one is right for you?

Swing by the Calgary Hitch Shop and let our experts measure, fit, and walk you through the best options for your next big trip.