Carriers bill the weight and size they measure
A parcel has a scale weight and a size weight. Carriers often bill the greater of the two. For many road services the size weight is length times width times height in centimetres, divided by 5,000. On that example a 45 by 30 by 16 cm box counts as 4.3 kg. The divisor is not universal. Check your own UPS tariff.
