Sardines are one of the first items that can be cooked with a requirement of level 1 Cooking. They can be cooked by using a raw sardine with a fire or a range. Sardines can be consumed to heal 200 life points. Players stop burning sardines at around level 35 Cooking. However, with the use of the cook's range, sardines will stop burning around level 30 Cooking.
Assuming no burning, each raw sardine cooked would yield a profit/loss of -74 coins.