- How long does baking powder last once opened? The precise answer to the question depends to a large extent on storage conditions; store in cool, dry area.
To maximize the shelf life of opened baking powder, keep the package tightly sealed after opening.
How long does opened baking powder last at room temperature? Properly stored, opened baking powder will generally stay at best quality for about 6 months.
Is baking powder safe to use after the "expiration" date on the package? Yes, provided it is properly stored and the package is undamaged — commercially packaged baking powder will typically carry a "Best By," "Best if Used By," "Best Before," or "Best When Used By" date but this is not a safety date, it is the manufacturer's estimate of how long the baking powder will remain at peak quality.
How can you tell whether opened baking powder is still good to use? To test whether opened baking powder is still potent enough to be effective: add one teaspoon of baking powder to one-third cup of hot water - if mixture bubbles, the baking powder is still potent enough to use.
Sources: For details about data sources used for food storage information, please click here