How to Tell When Your Sourdough Starter Is Ready to Bake With

You’ve fed your sourdough starter, there are bubbles in the jar, and you’re ready to make bread. But is your starter ready too?

For an established wheat-based starter, doubling after feeding is the benchmark to aim for when you’re starting out. A rise beyond doubling is a good sign too. The gold standard is to use your starter at its peak or just as it begins to fall.

Watch what your starter is doing rather than relying on a fixed number of hours. With practice, you’ll learn to judge the combination of rise, bubbles, aroma and changes at the surface. It doesn’t have to feel particularly light to be ready.

What does “active starter” mean?

When a recipe calls for active sourdough starter, it means starter that has been fed and allowed to ferment. Feeding provides fresh nutrients for the wild yeast and bacteria. Under favourable conditions, these microorganisms become active and multiply.

Yeast produces carbon dioxide, which helps your dough rise. The bacteria develop the acidity and flavour that make sourdough distinctive, and some also produce gas. We’re aiming for a healthy, active culture to give our dough a good start.

If you’re curious about the science, this explanation of microbial growth phases introduces the log, or exponential, phase of growth. A sourdough starter is a mixed culture, so its visible peak isn’t an exact measure of where every microorganism sits on that growth curve.

A few bubbles show that fermentation is happening, but they don’t tell the whole story. For wheat-based starters, the rise after feeding is a particularly useful sign.

Three signs to look for

1. At least doubling in volume

An established wheat starter should double or more after a suitable feed in warm conditions. Mark the starting level with a rubber band or your jar’s silicone band so you can follow its progress.

Use a straight-sided jar, or one close to it, and leave plenty of room above the starter.

Flour type and consistency affect how much gas the starter holds and how far it rises. A bigger rise is encouraging, but volume alone doesn’t measure yeast numbers or guarantee a taller loaf. Get to know what is normal for your starter. Gluten-free starters need a different approach, which we cover below.

2. Bubbles throughout the starter and at the surface

Bubbles throughout the mixture are a great sign that your starter is active. Look through the sides of the jar as well as at the surface. If the bubbles are hard to see through the glass, watch the top: you may see bubbles slowly swelling and escaping, almost in slow motion.

Bubble size varies with consistency and fermentation. In our experience, stiffer starters often show larger pockets, while slacker mixtures tend to show smaller bubbles. Small bubbles are also common early in fermentation and can become larger as the starter approaches its peak.

You don’t need one particular bubble size. Read the bubbles alongside the rise and the way the surface changes.

3. A surface at its peak or just beginning to fall

As the starter rises, its surface may look slightly rounded. Around its peak, that rounded surface can begin to flatten. At its peak, or only just beginning to fall, is our ideal baking window.

A “high tide” mark above the current level shows that the starter has risen and started to fall. A slight settling is fine; a substantial collapse means we recommend another feed before baking.

How long should it take after feeding?

There isn’t one reliable answer for every starter. Temperature has a big influence on fermentation rate, alongside flour, feeding ratio, hydration and the condition of the starter.

Keep your starter somewhere comfortably warm, ideally around 24–27°C. Avoid direct sun or uncontrolled heat, and check the actual temperature near the jar.

As a guide from our experience, doubling can take around 6–8 hours at 24°C, while a very active starter in favourable conditions may double in as little as two hours around 27°C. These are examples, not deadlines: temperature alone doesn’t determine the timing.

While you’re learning, check on it every couple of hours, and more frequently if it’s rising quickly or approaching its peak. Record when you fed it and watch how it develops over a few feeds under similar conditions.

Could you have missed the rise?

If you feed your starter before bed or put it away for a long time, it can rise and fall before you check it again. It may look as though nothing happened when it has actually completed a fermentation cycle.

Look for a high tide mark or residue above the current level, and check the aroma. Try a daytime feed when you can watch its progress. This is often the easiest way to learn its rhythm.

What can the aroma tell you?

Smell is another useful clue, especially if you weren’t there to see the rise. With our wheat starter, we generally notice:

• Approaching its peak: pleasantly yeasty.
• Only just beginning to fall: still pleasantly yeasty and slightly sour, with little difference from its peak.
• Further past its peak: still yeasty, but significantly more sour.
• Very hungry: a strong alcohol or acetone-like smell.

Use aroma alongside the rise, bubbles and feeding history. It helps you understand what has happened, but won’t pinpoint the exact moment of readiness on its own.

How hydration changes what you see

Hydration describes the amount of water compared with flour, by weight. A 1:1 ratio of flour and water is 100% hydration: for example, 50 g flour and 50 g water.

A wetter, slacker starter can release gas more easily, so you may see fermentation without much increase in height. A stiffer mixture can hold larger gas pockets, although an excessively dry mixture may struggle to expand.

Hydration can also affect fermentation speed, but wetter doesn’t always mean faster or stiffer always slower. Flour, temperature and feeding ratio work together.

For beginners, follow the feeding quantities below and aim for a thick consistency, like crunchy peanut butter. Once you know your starter’s behaviour, you can experiment with different ratios and consistencies.

A simple way to prepare starter for a loaf

For an established wheat starter maintained at 100% hydration, use a 1:1:1 feeding ratio of starter, water and flour by weight.

Digital scales are very important, especially when you’re starting out. Weigh all three ingredients. Equal cup measurements of flour and water don’t give equal weights, and consistent quantities make your starter much easier to understand.

1. Put 50 g starter into a clean jar.
2. Add 50 g water and 50 g bakers flour.
3. Mix thoroughly and mark the starting level.
4. Cover with a loosely fitted lid and keep around 24–27°C.
5. Watch for at least doubling and visible bubbles.
6. Use it at its peak or just as it begins to fall.

This gives approximately 150 g starter. If your recipe uses 100 g, you’ll have about 50 g left to maintain. Feeding an already 100% hydration starter with equal weights of flour and water keeps it at 100% hydration.

Need more starter for your bake?

You can keep a small starter and still prepare enough for a larger recipe. We suggest keeping around 50 g starter, then adjusting the flour and water you add to provide the amount needed for your bake.

The flour-to-water ratio depends on your starter and the flour you use. These are our recommended ratios for the flours we sell, measured by weight:

These ratios describe the flour and water added during feeding, not the amount of existing starter.

For a larger bake, make the combined weight of the added flour and water equal to the amount of starter your recipe needs. Your original 50 g then provides the portion you retain for next time.

Wheat example: your recipe needs 180 g starter

Wheat uses equal weights of flour and water, so divide 180 g in half:

• Start with 50 g wheat starter.
• Feed with 90 g bakers flour and 90 g water.
• This gives approximately 230 g starter.
• Allow it to ferment, then use 180 g at its peak or just as it begins to fall.
• Retain approximately 50 g for your next feed.

Rye example: your recipe needs 180 g starter

Rye uses five parts flour to six parts water, giving 11 parts altogether:

• Flour: 180 × 5 ÷ 11 = approximately 82 g.
• Water: 180 × 6 ÷ 11 = approximately 98 g.

Start with 50 g rye starter, then feed it with 82 g wholegrain rye flour and 98 g water. Once fermented, you’ll have approximately 230 g starter: use 180 g in your recipe and retain approximately 50 g.

Use digital scales and round to the nearest gram. A larger feed can change the time it takes to reach its peak, so watch your starter’s progress rather than relying on your usual timing.

These examples are for feeding an established starter. Follow the specific instructions for gluten-free starters or dehydrated-starter activation.

What if my starter has already fallen?

Falling is part of the normal fermentation cycle. It doesn’t automatically mean your starter is dead or that you’ve ruined it.

If it is only just beginning to fall, it is still in our ideal baking window. If it has fallen substantially, we recommend feeding again before baking. It can still ferment dough, but the dough may take much longer.

Take 50 g of the wheat starter into a clean jar and feed with 50 g water and 50 g bakers flour. Mark the level, keep it warm and let it rise again. Aim to use it at its peak or just as it begins to fall.

Before judging a starter as inactive, check for a high tide mark. You may simply have missed its rise.

Can I use starter straight from the fridge?

For our baking method, always feed your starter before using it to bake.

If your wheat starter has been stored in the fridge:

1. Remove it from the fridge and allow it to come to room temperature.
2. Take 50 g of starter and feed it with 50 g water and 50 g bakers flour.
3. Mix thoroughly and mark the starting level.
4. Keep it in comfortably warm conditions, ideally around 24–27°C.
5. Wait for it to at least double before using it. The gold-standard time is at its peak or just as it begins to fall.

A healthy, established wheat starter should reliably double or more when it has reached room temperature, been fed properly and is kept at the recommended temperature during fermentation.

If it hasn’t doubled, check the temperature, feeding quantities, flour and consistency. Also look for a high tide mark in case it rose and fell while you weren’t watching.

Does gluten-free starter need to double?

Not necessarily. The signs depend on which gluten-free starter you have and the flour you use to feed it.

For feeding, we recommend our Gluten-Free Bread and Pizza Flour or Gluten-Free 1–1 Flour. We’ve tested and specifically chosen these flours because they work well with our starters. We can’t guarantee the same results with other supermarket blends, as their ingredient combinations vary and often contain starches and gums.

Organic Gluten-Free Starter

Our Organic Gluten-Free Starter is fed on brown rice flour. If you continue feeding it with brown rice flour, the signs of fermentation can be much more subtle.

Look closely for very small bubbles and a layered appearance, with small gaps or separation within the mixture. The aroma should be pleasantly yeasty and slightly sweet. As it continues to ferment, slight smells of vinegar appear. The starter is still usable at this point, but this is a sign that it is reaching the later part of its usable window. You will not see the dramatic rise you would expect from a wheat starter.

Judging readiness comes down to recognising the combination of these small bubbles and the aroma. It takes a little practice, and our brown rice starter video demonstrates the visual cues to help you get familiar with them.

When fed with our recommended gluten-free flours, the Organic Gluten-Free Starter shows a much more noticeable rise and bubbles throughout the mixture, although it won’t always double.

Easy Rise Gluten-Free Starter

Once activated and fermenting, our Easy Rise Gluten-Free Starter also produces a beautifully yeasty and slightly sweet aroma and a noticeable rise, with bubbles visible throughout the mixture.

For either starter, follow its specific activation and feeding instructions. Get to know how it behaves with your chosen flour, rather than using doubling as the only test.

Quick questions

My starter has bubbles but hasn’t risen much. Is it ready?

For an established wheat starter, aim for at least doubling and use the bubbles as a supporting sign. Check its temperature, consistency and feeding history, and look for evidence that it rose and fell before you checked it. For gluten-free starters, use the flour-specific signs described above.

Do I need to catch the exact moment of peak rise?

No. Think of it as a useful baking window, not a split-second deadline. At its peak or just beginning to fall is the gold standard.

Should I throw away starter that has fallen?

Falling alone is not a reason to discard it. It is part of its normal cycle. If it has fallen substantially, take a portion and feed again before your next bake.

Every bake is a chance to learn

Using active starter gives your dough a good start, but you still need to watch the dough through fermentation. Flour choice, temperature and dough development all influence the finished loaf.

Use digital scales, take your time and note the conditions as you go, especially the temperature. A few simple notes about your starter, feeding quantities and fermentation will help you understand what worked and what you might adjust next time.

Most of all, have fun. Every bake is an opportunity to learn and improve. Your loaf doesn’t need to look like a bakery display to be a success. We really believe that if your loaf tastes great, then it is great.

When you’re ready, give our Beginner Sourdough Recipe a go and put what you’ve learnt into practice.

Let’s bake some bloody good bread!