A sourdough starter is ready when it reliably rises a lot after feeding and looks, smells, and feels very active. Most bakers look for consistent behavior over several feedings, not just one good day.
Key visual signs
After a feeding, the starter should at least double in volume within about 4–12 hours, depending on temperature. You should see many bubbles on the surface and along the sides of the jar, with a slightly domed top when it is at its highest point.
The texture should look light, spongy, and webby inside, almost like a honeycomb when you tip the jar or scoop some out. The jar will often feel lighter because of all the gas trapped inside.
Smell and texture checks
A ready starter smells pleasantly yeasty and mildly sour, without harsh or rotten odors like strong vinegar, nail polish remover, or cheese. If it smells sharp or unpleasant, it usually needs more regular feeds before baking with it.
When you stir or scoop it, it should feel airy and stretchy rather than thin and watery or thick and paste-like with no bubbles. A small taste should be tangy and slightly fizzy on the tongue, not bland or strangely bitter.
Float test and its limits
Many bakers use the “float test”: drop a small spoonful of starter (from the top, without stirring) into a glass of water; if it floats, it has enough gas and is likely ready. If it sinks, it often means it is underfed or has already passed its peak and fallen.
However, the float test is not perfect and can fail with very young, very stiff, or very liquid starters, so it is best used together with the visual and smell checks above. Many experienced bakers rely more on consistent doubling and good aroma than on the float test alone.
Consistency over time
A strong, mature starter does the same thing day after day: it roughly doubles or triples in a predictable time after feeding and shows the same bubbly, domed look at its peak. If the behavior is still irregular (sometimes rising, sometimes not), it usually needs a few more days of regular feeding before using it for bread.
Once your starter regularly rises and peaks on a schedule in your kitchen conditions, you can plan your dough mixing for when it is at or just before that peak for best oven spring.
