Whether you made pancakes from scratch or added water to a box mix, it seems that at least some leftover batter is inevitable. If you have a significant amount that you don't want or have time to cook up right way, you don't have to pour it down the drain. You can refrigerate or freeze most pancake batters that use baking powder or yeast as a leavening agent, with few problems.
Pour your leftover batter into a an airtight plastic container
Cover the container in a layer of plastic wrap. This adds an extra layer of protection to the batter.
Place the lid on the container, on top of the plastic wrap. Store it in the coldest part of your refrigerator. The pancake batter should keep for two days.
Pour the leftover pancake batter into a large freezer bag. Squeeze out as much air from the bag as possible.
Place the bag in the freezer. You can keep it in the freezer for up to three months.
Thaw the frozen batter by placing the bag in the refrigerator overnight or placing it in a bowl of warm water. Snip a corner of the freezer bag to pipe the batter onto the griddle.