Roof Load Limit Calculator

How it is calculated

All three fields are in kilograms: Roof load limit is the maximum roof load stated for your vehicle, Roof rack weight is the weight of the bars, rails or box itself, and Cargo weight is what you put on top.

total load = rack_weight + cargo_weight
remaining = roof_limit − total load
used % = total load ÷ roof_limit × 100

The roof limit must be above zero; rack and cargo can be zero but not negative, and all three fields must be filled in. Results are rounded to whole kilograms and the percentage to two decimals. If you are over the limit the remaining figure is shown as a negative number and the percentage goes above 100. The tool takes the limit you type; it does not know whether that is the figure for driving or the (usually different) figure for a parked vehicle, so read your handbook.

Common mistakes

• Leaving out the weight of the rack or roof box. The cargo-only figure looks fine, but the box itself may take a large part of the limit.
• Entering the weight in pounds. Every field is in kilograms, so a 165 lb limit is about 75 kg.
• Typing the vehicle's payload or the trailer limit instead of the roof load rating, which is usually much smaller.
• Ignoring a negative result. A remaining value such as -13 kg means you are 13 kg over the limit, not that the roof has spare capacity.
• Forgetting extra items fixed to the roof, such as a bike carrier, spare wheel or kayak cradles, which count as part of the total load.