Your baking powder might be dead – here’s the 30-second test to find out - Ingredient Guide

by India Tarasin

Jun 02, 2026

Time to rise and shine, people.

You’ve taken the time to carefully plan and prepare a special afternoon tea treat, measuring out every ingredient and following each step with care, only to pull your bake from the oven to find it disappointingly flat. It’s enough to make you throw in the apron all together.

But before you start second-guessing your skills or cursing the recipe, there’s another often overlooked factor that could be behind that lacklustre rise.

Yes, that little unassuming tin of baking powder could be the culprit. You see, it’s possible it might no longer be ‘active’.

The good news is, there’s an easy 30-second test you can do while reading this very article, to check whether your baking powder still has life left in it.

How long does baking powder last?

Generally, baking powder performs best within six months of opening. But this isn’t a hard and fast rule – once opened, a little care in how you store and handle your baking powder can go a long way.

The expiry date is a useful guide, but it isn’t the only sign of freshness – baking powder can start to lose its effectiveness well before that date, gradually weakening as soon as the seal is broken. How quickly this happens depends on factors like heat, humidity and how securely the lid is closed after each use.

To help extend its life, keep baking powder in an airtight container stored somewhere cool, dry and dark – such as a pantry shelf rather than a spot near the stove where heat and steam can creep in.

It’s also worth being careful when measuring it out: always use completely dry utensils, as even a small amount of moisture can trigger a reaction inside the container and gradually reduce a baking powder’s rising power.

Five scones with cream and marmalade sit in a line on a wooden block with a glass jar of marmalade to the left, and a pale background behind. — CWA scones.

How to test if your baking powder is still active

Your baking powder might look completely fine sitting in the pantry, but if it’s past its best or no longer active, it can silently sabotage your bake.

Thankfully, there’s a quick and easy test you can do that will tell you in seconds whether it’s still good to use. So what’s the trick?

Pour 1/4 cup (60ml) of boiling water over 1/2 teaspoon of baking powder. If the powder starts to fizz, it’s still active and ready to use. If nothing happens, it’s lost its lift – and it’s time to get a new one before your next bake.

Even a slightly weakened batch of baking powder can lead to dense cakes, flat scones or muffins that don’t quite reach their potential. This easy test is one of those small checks that can make a big difference to your end result.

Once you’ve confirmed your baking powder is still active, you can bake with confidence, knowing your raising agent will do its job properly. Pair it with accurate measuring and a gentle hand when mixing, and you’ll get that light, airy texture every time – exactly what afternoon tea baking is all about.

So there you have it. Whether you’re wanting light and airy scones or the perfect sponge, this fail-safe trick will work every time.

Get that whisk ready!