About 1 to 2 days, covered, in the fridge. Pancake batter made with eggs and milk is perishable, so it must be refrigerated. The bigger problem is usually flat pancakes: baking powder starts reacting as soon as it gets wet, so the batter loses some of its lift the longer it sits.
Storing pancake batter
- Cover it tightly, or pour it into a jar or squeeze bottle.
- Refrigerate it right after mixing. Don’t leave batter at room temperature for more than 2 hours.
- Use it within 1 to 2 days. Throw it out if it smells sour or has turned grey.
Some separation and a little darkening on top are normal. Stir it gently before cooking.
Making stored batter rise better
- Stir it gently, without beating out the remaining bubbles.
- Add a little fresh baking powder (about ½ teaspoon per cup of flour in the recipe) if the batter looks flat.
- Thin it with a splash of milk if it has thickened overnight.
Better ways to prep ahead
- Mix the dry and wet ingredients separately the night before. Keep the wet mix in the fridge, then combine them in the morning. This gives the fluffiest pancakes.
- Cook all the pancakes and freeze them. Lay them flat to freeze, then bag them. Reheat them in a toaster or microwave.
Quick answers
Can I leave pancake batter out overnight?
No. Batter with eggs and milk shouldn’t sit out for more than 2 hours. Throw it away.
What about batter made from a box mix?
If you added eggs or milk, the same 1 to 2 days applies. Check the box, too.
Can I freeze pancake batter?
You can, but the pancakes come out flatter. Freezing cooked pancakes works much better.
Source: USDA Food Safety and Inspection Service, Leftovers and Food Safety (2-hour rule).