The Real Reason Your Baked Goods Won't Rise (It's Not the Recipe)

It's December, you're gearing up to bake your annual holiday cookies, and without a second thought, you reach for the dusty containers of baking soda and baking powder that have been living in the back of your cabinet since last year, or maybe longer. You mix your dough, portion it, slide the tray into the oven, and 20 minutes later, you are met with squat, pale cookies.

What happened? Did you miss an ingredient? Misread the recipe? Is it just a bad recipe?

Before you fire off an email or post a complaint on Reddit, take a minute and check your leaveners, because the problem might be the age of your baking soda and baking powder.

What These Powders Actually Do

Both baking soda and baking powder are chemical leaveners. They're powerful ingredients that, when used in your baked goods, generate carbon dioxide, causing them to rise and affecting browning, texture, and flavor.

Baking soda (pure sodium bicarbonate) requires an acid—such as buttermilk, yogurt, brown sugar, or cocoa powder—to react with it, release CO₂, and help the batter rise. It also raises pH, which encourages deeper browning.

Baking powder contains baking soda, an acid salt, and cornstarch. It only needs liquid and heat to create lift, which is why it's often the primary leavener in many cookies, cakes, and quick breads.

They're both extremely shelf-stable pantry items. There's a good chance you have an open container of each sitting around right now. But "shelf-stable" doesn't mean "eternal." And according to manufacturers, these products last about one year after opening. But my testing (and your experience, if you've ever baked flat muffins) says otherwise.

Why Age Matters—Even Before the Expiration Date

Chemical leaveners begin to lose potency the moment they're exposed to air and humidity. That slow decline isn't noticeable day to day, but over time, its impact on baked goods is significant.

Many bakers rely on a warm-water "bubble test" to check whether baking powder is still good: Add a spoonful to warm water, and if it fizzes, it's considered usable. The problem is that this test only shows that the powder can react—not how powerfully it reacts. A weak fizz still counts as passing, even if the baking powder has lost a significant portion of its actual leavening strength.

To figure out exactly when open baking soda and baking powder stop doing their best work, I ran a 10-month test using our Buttermilk Biscuit recipe, which strategically uses both baking powder and baking soda for sky-high lift and golden color.

The Test

I purchased brand-new containers of baking soda and baking powder, wrote the opening date on each (a habit I highly recommend), and then baked monthly batches of biscuits. The control batch always used freshly opened powders. The others used increasingly older containers. I isolated the variables by swapping only one leavener at a time to determine whether the biscuit failures came from the baking soda, the baking powder, or both.

By the end of 10 months, I had a spreadsheet full of rise measurements, crumb notes, and color comparisons, and a pretty clear answer.

The Results

Baking Powder: Decline Starts at Six Months

The most striking changes came from the baking powder tests. Biscuits made with powder less than six months old rose tall and evenly. At the six-month mark, I began to see slight but noticeable shrinking: biscuits that were just a bit shorter and less dramatic. By ten months, the decrease in lift was unmistakable, and biscuits were about half the height of those made with freshly opened powder.

This echoes results from previous Serious Eats testing: Even though every powder "passed" the classic warm-water bubbling test, they absolutely did not perform the same in baked goods. The water test indicates whether it's "alive." It does not indicate whether it's strong.

Baking Soda: Browning Drops Off After Six Months

Baking soda's decline was subtler. Rise remained fairly consistent across the first several months, but the degree of browning was not. After six months, side-by-side biscuit tests showed a clear difference: Biscuits made with older baking soda baked up paler and less golden.

Since the baking soda influences pH—which influences Maillard browning—that loss of oomph showed up right on the surface.

So, How Long Are They Good?

Based on controlled testing (and many, many biscuits):

• Replace both baking powder and baking soda every six months.
• Ignore the bubbling-water test—it's not reliable for measuring true leavening strength.
• Write the opening date directly on the can or box.
• Store them in a cool, dry cabinet.
  

If you bake frequently, consider buying smaller containers, so you use them up while they're still at full power.

The Takeaway

If your bakes are coming out squat, pale, dense, or just "off," the recipe may not be the issue. Your leaveners may simply be past their prime. Baking soda and baking powder are decently shelf-stable, but they absolutely do age—and your baked goods will tell you when it's time to toss them.

So before holiday baking season kicks in, do yourself a favor and check those dates, grab fresh containers, and give your biscuits, cookies, and cakes a chance to rise to the occasion.