Does Flour Go Bad? An Explainer on Storage and Expiration

By Julie Harans

Unless you’re a professional pastry chef or an avid baker, chances are you purchase one bag of flour at a time and use it in relatively small amounts. But did you ever stop to wonder if that bag you just dug out of the back of the cupboard was fresh enough to use? Can you even remember when you bought it? Does flour expire? For such a universal pantry staple, there's a surprising amount of ambiguity about whether wheat-based flour goes bad. And while some resources may point to a use-by range of three to eight months, the reality isn't so simple. Not to mention, that's a pretty wide margin for error—and who wants to replace their flour every three months? To find out how long you can actually hold on to your flour stash, we turned to pastry chef and author of Mother Grains: Recipes for the Grain Revolution, Roxana Jullapat, and assistant professor of food science at Cornell University, Abby Snyder.

In short, longer than you’d think. According to Snyder, questions of food expiration come down to two factors: safety and quality—and safety isn't much of a concern here. Flour is a low-moisture food, meaning it doesn't contain enough water to support microbial growth. As such, it's considered extremely shelf stable and unlikely to become less safe to eat over time. And although flour may contain pathogens like E. coli, which can survive for long periods in storage, the risk in ingesting the flour won't increase—but it's certainly why we recommend heating flour before consuming it, like in our recipe for ready-to-eat cookie dough.

Quality is less clear-cut, and Snyder typically avoids giving specific time estimations. But you can expect most refined white flours (all-purpose, bread flour, 00 flour, cake flour, etc.) to keep for a year or more if stored properly (i.e., kept dry in an airtight container in a cool, dark place). "I definitely have flour in my pantry that's over a year old," Snyder says, "and it's fine."

Just like a bottle of olive oil can turn rancid in your pantry, the fats in some flours can spoil. The homogenous, highly refined all-purpose flour commonly found in grocery stores contains less fat than some gluten-free flours, like buckwheat flour, coconut flour, and nut flours, like almond flour. Because of their higher fat content, these flours may be shorter-lived—in Jullapat's experience, higher-fat flours can turn less desirable about two times faster than all-purpose flour.

For whole wheat flour and other whole grain flours, like rye and spelt, the bran and germ (the parts of the kernel removed during white flour's refinement process) may cause faster spoilage. These flours contain fats susceptible to rancidity which can contribute to shorter shelf life.

Self-rising flour, which contains baking powder, is a special case. Snyder advises that while it won't "go bad" by standard definitions, the leavening agent could become less potent over time.

No matter what variety you're concerned about, Snyder assuages that, by and large, the shelf life of flour is extensive. She also says that it's not really food safety you need be concerned about but quality deterioration, which she posits is "somewhat subjective."

Use up your flour stash with our easiest baking recipes, like this secretly-vegan chocolate cake.

The expiration date on the package will give you a clue, but don't fret too much over it—your "expired" flour won't go bad when the clock strikes midnight. Snyder says there's some pushback against best-by dates, which contribute to food waste, causing buyers to throw out ingredients prematurely. Treat the printed expiration date as a guideline, not an ultimatum.

Here's what to look for: If your flour smells unpleasant, this could be a sign that the fat present in the flour has oxidized. This rancid flour smell could be musty, sour, or even just slightly off (some Epi staffers liken the aroma to wet cardboard or Play-Doh). And once you’ve experienced noxious old flour, you’ll know: "If you've smelled it before," Jullapat says, "you'll be like, ‘oh, yeah, this is gone.’"

Another enemy of flour freshness is moisture, which may be indicated by clumping or an overall "weird texture," as Jullapat puts it. There could be mold in there—you may even see it. If that's the case, toss the whole thing; don't try scooping out the top to save the rest.

Yellowing can be another sign your flour is bad. And let's not forget the most obvious indicator: Bugs. Weevils are common flour invaders, so keep an eye out and ditch the flour if you notice a pest infestation. Freeze the container for at least three days before you throw out the flour to kill any critters. That way, they won't make their way out of the trash can (or compost bin) and back into your kitchen.

Both Jullapat and Snyder recommend transferring fresh flour from the original packaging to an airtight container right after purchasing, like a zip-top freezer bag or a glass canister like a mason jar. Don't forget to label it—and include the date. You may make it through the container before it's time to replace, but this is good practice for any pantry staple you’re storing—especially if you’re an avid baker or "flour curious" like Jullapat, who collects various unique varieties that can be hard to distinguish from one another on sight alone.

You can store flour in a cool, dark, dry place like your pantry, but if you keep flour in the fridge or freezer, it will last even longer. (If you go the latter route, using a silicone or plastic bag makes the most sense from both a space-saving and safety perspective; you wouldn't want a glass jar of flour falling from the freezer to your tiled floor for a fun Sunday surprise.) But consider your recipe: If it calls for room-temperature butter or eggs, let the flour temper a bit. If you’re making something that benefits from chilled ingredients, like an all-butter pie dough, use the flour straight from the cold, for what might be an even better result.