The first thing you should know about the capacity of a washing machine is the advertised weight refers to dry clothes. A "7kg washing machine" thus carries in her tub 7 pounds of dry clothes.
Another important factor is the volume occupied by pieces of clothing. Articles with foam padding and synthetic fabrics may be below the limit of capacity (by weight), but the volume is greater than the capacity of the basket and can not allow complacency weight indicated for this type of clothing.

Special attention to heavier clothes like jeans and towels. They should be arranged in the washing basket with some slack. When compressed harm the process of washing and centrifuging for not distribute the weight evenly.
Therefore: Always dry clothes, underweight indicated in the manual and arranged so well spread around the basket are fundamental not only to the washing process, and to ensure the durability of your appliance.