You've been feeding your starter religiously for days (or weeks!), watching it bubble and grow, but here's the million-dollar question that keeps every new sourdough baker up at night: Is it actually ready to bake with? The good news is that your starter will give you clear signals when it's ready to work its magic. Let me show you exactly what to look for.
The Float Test: Your Starter's Swimming Lesson
This is the gold standard test that bakers have relied on for generations, and for good reason—it works. Here's how to do it: take a small glass of room-temperature water and gently drop a spoonful of your starter onto the surface. If it floats, congratulations! Your starter has developed enough gas bubbles to stay buoyant, which means it's strong enough to lift bread dough.
If it sinks like a stone, don't panic. This simply means your starter needs more time to ferment, or perhaps it's past its peak (more on timing in a moment). The float test isn't foolproof, but it's an excellent quick check before you commit to a full bake.
The Volume Test: Doubling Down on Success
A truly active starter should double in volume within 4-8 hours of feeding at room temperature (around 21-24°C or 70-75°F). This is one of the most reliable indicators of strength. I recommend using a rubber band or a piece of tape on your jar to mark the level right after feeding, then watch as your starter climbs.
The exact timing depends on your environment—warmer kitchens will speed things up, while cooler spaces slow them down. What matters is consistent, predictable growth. If your starter reliably doubles, it has the oomph to raise bread.
The Peak Dome: Timing Is Everything
Here's something many beginners miss: you want to use your starter at or just before its peak rise. Look at the top surface. When your starter is rising, it will have a beautifully domed top. At peak, that dome will just start to flatten or develop a slight concave dip in the center. This is prime time for baking.
If you wait too long and the starter collapses back down, it's exhausted its food supply and started to decline. You'll see a more pronounced concave surface, and it might even separate with a layer of liquid (hooch) on top. A collapsed starter can still work in a pinch, but you're not getting its best performance.
The Bubble Test: What's Happening Inside
Pull your jar away from the wall and look through the side. A ready-to-bake starter should be full of bubbles throughout—not just on top. You want to see a network of bubbles of various sizes, indicating active fermentation at every level. This bubbly structure is what creates the open crumb we all love in sourdough bread.
If you only see a few lazy bubbles on the surface, your starter needs more time or more consistent feedings to build strength.
The Smell Check: Your Nose Knows
A healthy, active starter at peak should smell pleasantly tangy and yogurt-like, perhaps with fruity or slightly alcoholic notes. It should make you think "yum" not "yikes." If it smells strongly of nail polish remover (acetone) or vinegar, it's likely over-fermented or needs more frequent feedings to keep the yeast-to-bacteria ratio balanced.
A truly unpleasant smell—like rotting food or anything that makes you recoil—indicates something has gone wrong, though this is rare if you're maintaining a regular feeding schedule.
The Consistency Sweet Spot
When your starter is ready, it should have a thick, stretchy consistency—like a very thick pancake batter or even closer to a soft dough if you maintain a stiffer feeding ratio. When you stir it, it should offer some resistance and create glossy, stretchy ribbons that hold their shape for a moment before settling.
A starter that's too thin and watery, or one that's separated into layers, hasn't developed the gluten structure and fermentation strength you need for bread.
How Old Should Your Starter Be?
If you've just started your starter from scratch, you'll need patience. A brand-new starter typically needs 7-14 days of consistent daily feedings before it's strong enough for bread baking. During the first week, you'll see activity that comes and goes—this is normal as different bacterial populations compete for dominance.
Don't be fooled by early activity around days 2-3; this is usually a false start caused by different bacteria. True, reliable sourdough fermentation typically kicks in around day 5-7. You'll know you've arrived when your starter shows consistent, predictable doubling day after day.
The Ultimate Test: Bake With Confidence
Once your starter consistently passes these tests—floating, doubling in 4-8 hours, full of bubbles, pleasantly tangy, and thick—you're ready to bake. But here's my insider tip: your first bake is also a test. Don't stress about perfection. Even if your starter is somewhat weak, you'll still get bread, and you'll learn volumes about how your specific starter behaves.
Many bakers wait too long, afraid their starter isn't "ready enough." If you're seeing reliable doubling and good bubble structure, go for it! Bread baking is the best teacher, and your starter will only get stronger with time and regular use.
Creating Your Readiness Routine
I recommend establishing a pre-bake routine that works for your schedule. Most bakers feed their starter the evening before they plan to mix dough, then use it the next morning when it's at peak—typically 8-12 hours later at 21°C (70°F). In summer or warmer kitchens at 24-27°C (75-80°F), this might be just 4-6 hours.
Watch your starter over several feeding cycles and note when it peaks. This is your personal starter's rhythm, and knowing it will make you a better baker than any generic timeline ever could.
When In Doubt, Check the Basics
If your starter isn't showing these ready signs, revisit the fundamentals: Are you feeding it with consistent ratios (I recommend 1:1:1 for building strength—equal parts starter, flour, and water by weight)? Is your water chlorine-free? Is the temperature in a good range for fermentation?
Sometimes the answer is simply more time. A young starter or one that's been neglected needs patience and consistent care to rebuild its population of wild yeast and beneficial bacteria.
Trust the Process (And Your Starter)
The beautiful thing about sourdough is that it's been made successfully for thousands of years, long before pH meters and precise thermometers. Your ancestors relied on the same signs you're learning to read: volume, bubbles, smell, and texture. Trust these indicators, trust your observations, and most importantly, trust that practice makes perfect.
Your starter is ready when it shows you consistent strength and vitality. Once you see those signs, it's time to get your hands floury and make some bread. The journey from starter to loaf is where the real magic happens!