How to tell when your sourdough starter is ready

Your sourdough starter is ready when it reliably doubles within 4-8 hours of feeding, smells tangy and slightly sweet rather than harsh, and looks domed and bubbly at its peak. If “is my sourdough starter ready” is the question, the most honest answer is to watch one full feed cycle and judge the dough by feel, not the clock. Timings here are estimates.

Watch the rise and fall

The single best signal is the rise. After you feed a healthy starter, it should climb, peak, then slowly sink back. Mark the jar level right after feeding with a rubber band or a strip of tape, then check it over the next several hours.

• A starter that doubles or triples at a predictable point is producing enough gas to leaven bread.
• A starter that barely moves, or takes 12+ hours to peak, needs more feeds or a warmer spot (ideally 24-26C / 75-79F).
• A starter that rises and collapses fast, then smells sharp, is hungry. Feed it sooner next time.

You want to catch it at or just before the peak. That is when yeast activity is highest. If you are unsure about ratios and timing, see feeding your starter.

The float test, and its limits

Drop a teaspoon of starter into a glass of room-temperature water. If it floats, it is full of gas and likely ready. If it sinks, give it more time.

The float test is useful but not perfect. A starter past its peak can deflate and sink even though it baked fine an hour earlier. A wet, slack starter sometimes sinks despite being active. Treat a float as a green light and a sink as a “look closer,” not a verdict. The rise pattern is more trustworthy.

Smell and texture

Smell tells you what the microbes are doing.

• Ready: yeasty, tangy, a little fruity or like plain yogurt.
• Hungry or off-balance: sharp acetone, nail polish, or strong vinegar. Often paired with a layer of dark liquid (hooch) on top. Pour it off, feed, and wait.

Texture should be airy and stretchy at peak, webbed with bubbles of different sizes through the jar. Scoop a little: it should feel alive and slightly elastic, not flat batter and not a dense paste.

When it is ready to bake

A new starter usually needs 7-14 days of regular feeding before it can raise a loaf. Look for this run of behavior across two or three feeds in a row:

Signal	What you want
Rise	Doubles in 4-8 hours, predictable peak
Smell	Tangy, mild, slightly sweet
Bubbles	Many, evenly spread through the jar
Texture	Domed top, stretchy and airy

One good rise is encouraging. Three in a row means you can trust it. Build your levain (or use the starter directly) when it is at or near peak, since that is when it has the most lift to give your dough.

A few practical notes:

1. Warmth speeds everything up. The same starter can peak in 4 hours at 26C / 79F and 10 hours at 18C / 64F.
2. Hydration changes the look. A stiffer starter rises taller and holds shape; a 100% hydration starter looks looser and bubblier. To dial in numbers, the hydration calculator helps.
3. If you keep your starter in the fridge, take it out and run one or two feeds at room temperature before you plan to bake.

Trust the pattern over any single test. When the rise is predictable, the smell is pleasant, and the float test agrees, your starter is ready to bake.