Introduction
Choosing the right roof box size is about more than just litres on a spec sheet. It is about matching capacity to your car, your luggage, your family and the type of journeys you take. This guide walks through real-world examples and simple rules so you can choose a roof box that fits properly and works hard on every trip.
Roof Box Sizes Explained
Most roof boxes sit between 250L and 600L, with different ranges suited to different vehicles and uses.
Small Roof Boxes (250–350L)
Best for couples, small hatchbacks and light luggage. These are ideal for weekend breaks, airport runs or occasional extra storage.
Medium Roof Boxes (350–450L)
The most popular size for families of three to four. They balance capacity and handling well and work with many family cars and crossovers.
Large Roof Boxes (450–600L)
Designed for larger families, camping holidays and long road trips. These boxes can handle multiple suitcases, camping gear or specialist kit like skis in long, narrow models.
Match the Box to Your Car
Your car size and roof length are the foundation of your decision.
Small Cars (e.g. Fiesta, Corsa, Polo)
Recommended size: 300–380L. A compact box keeps weight sensible and avoids excessive overhang or wind noise.
Medium Cars (e.g. Golf, Focus, Civic)
Recommended size: 380–450L. This range delivers enough space for most families without feeling unwieldy.
Large Cars (Estate, SUV, MPV)
Recommended size: 450–600L. Larger vehicles can safely support bigger boxes and longer loads when used within weight limits.
Consider Your Family or Group Size
A simple way to narrow down options is to think about how many people you typically travel with.
- Couples: 300–380L is usually sufficient.
- Family of 3–4: 380–450L covers most situations.
- Family of 5+: 450–600L gives flexibility for long trips and bulky items.
Match Size to Trip Type
City Breaks and Short Stays
A smaller box (around 300–380L) is usually enough for a couple of cases, coats and extras.
Camping Holidays
Larger boxes (450–600L) shine here. Tents, mats, sleeping bags and cooking gear are bulky, and extra height and length help.
Ski Trips
Look for a long, narrow box in the 430–500L range. The length matters more than the total volume when carrying skis or snowboards.
Beach and Family Holidays
Boxes in the 380–450L range offer a good mix of volume and practicality for chairs, toys, towels and soft bags.
What Fits in Different Sizes? Real Examples
Around 320L (Small Box)
- Two medium suitcases.
- One small soft bag.
- Coats or bedding.
Around 420L (Medium Box)
- Two to three suitcases.
- Children’s bags or toys.
- Beach or camping accessories.
500L+ (Large Box)
- Three to four suitcases.
- Pushchair or stroller.
- Sleeping bags, mats and bulky gear.
Once you’ve chosen the right size, follow our Roof Box Packing Checklist to load it safely and efficiently.
Do Not Ignore Weight Limits
Size is only half the story. Your car has a dynamic roof load limit which caps how much weight you can safely carry on the roof while driving.
This total includes:
- The roof box itself.
- The roof bars.
- All luggage inside the box.
Always check your vehicle handbook, roof bar instructions and roof box manual to stay within the lowest rated limit.
Aerodynamics and Shape
Two boxes with the same volume can behave very differently on the road.
- Long, narrow boxes are ideal for skis and long items, and tend to work well on estates and SUVs.
- Shorter, wider boxes suit general luggage and hatchbacks.
More aerodynamic designs often reduce noise and fuel consumption, especially on motorways.
Common Mistakes When Choosing a Size
- Buying the biggest box available without checking your car’s length or weight limits.
- Choosing the wrong shape for your main use, such as buying a ski box when you mainly carry bags.
- Ignoring how the box opens, making service-station access awkward.
- Overlooking garage clearance, especially with tall SUVs and large boxes.
Simple Size Decision Guide
- Small car, couple, short trips: 300–380L.
- Family car, 3–4 people, mixed trips: 380–450L.
- Large car, 5+ people or camping: 450–600L.
Conclusion
The right roof box size depends on your car, your companions and how you travel. Once you understand how capacity, shape and weight limits work together, choosing becomes much easier. Use this guide alongside compatibility checks and packing advice to find a box that fits your lifestyle as well as your vehicle.