Our packets of crisps are filled by weight. You should always find that the packets weigh the grammage stated on the packet. However, there is a very good reason for the packets not being filled right to the top. Crisps are very fragile and can get crushed very easily. To try and prevent this from happening, we put air in the packs before they are sealed to act as a cushion for the product during transit. This does mean that the packets have to be a bit bigger than the contents.