When is Sourdough Starter Ready to Use?

Sourdough baking can feel like a science experiment, but once you get the hang of it, it becomes second nature. One of the most common questions I hear from new sourdough bakers here on the blog and in our facebook group: When is my starter ready to bake with?

If you’ve been wondering the same thing, this guide is here to help you out. I’ll share the key signs to look for and a few tips to make the process easier, purposefully avoiding digging deep into the topic so the post gives you everything you need without overwhelming you!

What Makes a Starter “Ready”?

A sourdough starter works by cultivating natural yeast and bacteria that ferment a mix of flour and water. This fermentation produces carbon dioxide (which is responsible for those bubbles!), organic acids, and that characteristic flavor we love in sourdough bread.

A ready starter is one that’s active and strong enough to leaven your dough. Essentially, it should be able to lift your bread and give it that airy crumb. Here are the cues to help you know your starter has reached this state.

1. Visual Cues

Bubbles

An active starter is a bubbly starter. Take a look at the surface – you should see lots of bubbles. If you’re using a glass jar, check the sides and bottom for even more bubbly activity. These bubbles are a sign that the wild yeast in your starter is happily releasing carbon dioxide.

Rising in volume

Another easy-to-spot sign is growth. After feeding, your starter should double or even triple in size. Use a rubber band to mark the level of your starter after feeding, and watch how far it rises. Keep in mind that the time it takes to double can vary based on the temperature of your kitchen and the hydration of your starter.

Tip: If your starter is very hydrated (think thin and runny), it may not hold bubbles well enough to visibly double. In this case, focus on other cues like bubbles and smell, or simply feed it more flour next time.

2. The Smell

The smell of your starter is another great indicator of its readiness (and it comes in handy if you’re like me and forget to put a rubber band around your starter jar). A ripe starter often smells tangy and sour, with a hint of yeastiness. If it smells like nail polish remover or very acidic, it’s likely over-fermented and hungry for a feeding. Don’t worry if it doesn’t smell sweet or fruity – that’s more of a myth than a rule in my opinion.

3. The Float Test

The float test is a classic, but it’s not foolproof. To try it, spoon a small amount of your starter into a bowl of water. If it floats, it’s ready to bake with. However, starters with high hydration might not float because they’re too runny, even if they’re active and ready to go. Consider this test a bonus cue rather than a rule.

Tip: If you stirred down your starter before doing the float test, it’s completely normal the starter won’t float!

4. Timing: When to Use Your Starter

Many recommend using your starter when it’s at its peak height, just before it begins to collapse. This is when the yeast is most active. However, I’ve found great results even when using the starter slightly past its peak. A starter that’s just starting to fall is still fully active and fermented, and it works great in dough. Plus, you can be sure it actually reached it’s peak, since it’s technically a little bit past it.

5. Don’t Overthink It

The truth is, sourdough baking is more forgiving than many people realize. If your starter checks most of the boxes – bubbly, rises in volume nicely, pleasant smell – it’s probably ready to use. The worst-case scenario? Your loaf might turn out a little flatter than you’d like. That’s okay! Sourdough baking is all about learning and getting better with each bake.

Tips for Helping Your Starter To Be Ready

If you want to time your starter’s readiness to fit your baking schedule, adjust the feeding ratio. A smaller feeding ratio (like 1:1:1) will make your starter peak faster, while a larger ratio (like 1:5:5) slows it down. Experiment to find what works best for your kitchen temperature and routine.

Try This: If you manage to put your starter in the fridge right around the time it peaks, you can use it for two or three days straight from the fridge with great results! I do this all the time to add flexibility to my sourdough baking routine.

Quick Recap

• Look for bubbles and volume growth.
• A tangy, sour smell is a good indicator that the starter is fermenting nicely.
• The float test can be a helpful (but not essential) test.
• Use your starter at or (even better in my opinion) slightly past its peak.
• Don’t stress too much – practice makes perfect. Try it and see how it goes.

Ready to Bake?

If your starter checks the boxes above, it’s time to mix some dough! And if you’re new to sourdough baking, I’ve got a beginner-friendly recipe on my blog to get you started. Don’t forget to enjoy the process and don’t let the flops discourage you. We all started out with flat loaves.

Got questions about your sourdough starter? Leave them in the comments – I’m always happy to help!