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Heading South: How to Choose the Right Roof Box Length

When Mainz families call us looking for a roof box for summer vacation, one question keeps coming up: "Is a 450 enough, or do I need the 500?" Volume in liters alone doesn't really help – what usually matters is the interior length. And that varies significantly between boxes.

Why interior length is the more important number

A 450-liter volume sounds respectable, but if you want to transport skis or a surfboard, only one number counts: how long is the interior? We regularly see customers select by volume, then realize their 190 cm skis have to be wedged in at an angle.

Here are the typical interior lengths of our four sizes:

  • 300 liters: approx. 177 cm interior length
  • 450 liters: from approx. 182 cm interior length
  • 500 liters: from approx. 197 cm interior length
  • 600 liters XXL: from approx. 222 cm interior length

Which length for which gear?

Suitcases: Standard suitcases are 70–80 cm long and fit in every box. Volume matters more than length here.

Skis:

  • Skis up to 175 cm: fit the 300-liter box
  • Skis up to 182–190 cm: go for 450 liters
  • Skis 190–200 cm: 500 liters
  • Touring or cross-country skis over 200 cm: 600-liter XXL

Tip: measure your skis including bindings before booking. Some touring skis are longer than expected.

Snowboards: Typically 150–165 cm long, fit any box.

Surfboards: Most shortboards (up to ~200 cm) fit in a 500-liter box. Longboards over 220 cm need the XXL.

Strollers, buggies: Folded they're usually under 100 cm. Length isn't the constraint; width and height are.

Heading south: what works in practice

For classic Southern European family trips (combustion-engine car, autobahn, summer), the 450 or 500-liter boxes are the most common picks. Reasons:

  • Enough room for suitcases, beach gear, kids' essentials
  • Moderate empty weight (12–14 kg) – the roof handles this reliably
  • Still good aerodynamics – extra fuel consumption on the autobahn is typically 1–1.5 liters per 100 km

If you're unsure, go with the 500-liter – the price difference is moderate and you have reserve capacity.

When the 600 pays off

The XXL box isn't right for every family. It makes sense for:

  • Ski gear for four people plus additional luggage
  • Long trips (3+ weeks) with lots of changes of clothes
  • Bulky sports equipment (windsurfing, sailing, fishing gear)
  • Very large families (5+ people) on vacation

With smaller vehicles (compact class), check before booking whether the roof rack and allowed roof load can handle the XXL. For station wagons and SUVs, this is usually not an issue.

Our recommendation

Measuring beats guessing. Before booking, lay down your bulkiest item (ski, surfboard, tent bag) and note the length. That number plus 5 cm of buffer – that's your minimum interior length.

For questions about which size to pick, give us a call. Our pickup location in Darmstadt is reachable from Mainz via A60/A67 in about 40 minutes.

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