Cooking time completely depends on the size of the salmon you're cooking. For individual fillets that are about 6oz, it takes about 16 to 18 minutes to bake them in foil at 400°F. If making a side of salmon (about 2 lb.) then bake it at 400°F for about 22 to 25 minutes depending on the thickness. Making baked salmon in tin foil helps with the tenderness of the salmon and won't let it dry easily.