Is My Sourdough Starter Ready to Bake?
1. Has your starter risen since its last feeding?
How to Know When Your Sourdough Starter Is Ready to Bake
TL;DR: A sourdough starter is ready to bake with when it doubles within 4–8 hours of feeding at 75–80°F, smells pleasantly tangy, has bubbles throughout, and passes the float test. If it doesn't double, the most common cause is temperature — not starter quality.
Every beginner stands over that jar at some point wondering. Did I do something wrong? Is it dead? Is it ready?
Most of the time the answer is: it's fine, it's just not quite there yet. Here's how to know for sure.
The 5 Signs Your Starter Is Ready
- It doubled within 4–8 hours of its last feeding at 75–80°F
- The top is domed — slightly rounded at peak rise, not flat or collapsed
- Bubbles throughout — not just foam on the surface, but throughout the entire jar
- Smells pleasantly tangy — like yogurt, mild vinegar, or ripe fruit
- Passes the float test — a small spoonful dropped in room-temperature water floats
What the Float Test Actually Tells You
A starter floats when it's full of carbon dioxide gas from active fermentation — the same gas that will make your bread rise. If it floats, there's enough active yeast activity to leaven dough. If it sinks, fermentation hasn't peaked yet.
Important caveat: the float test isn't foolproof. A 2020 survey of professional sourdough bakers found that roughly 20% of healthy, active starters still sink at peak — especially stiff starters or very active cultures that are slightly past peak. Use it as one signal, not the final word.
Why Your Starter Isn't Ready Yet
If your starter consistently fails to double after 24 hours, here are the most common causes in order of likelihood:
| Problem | Fix |
|---|---|
| Kitchen too cold (below 70°F) | Move to top of fridge or oven with light on |
| Chlorinated tap water | Switch to filtered or spring water |
| All-purpose flour only | Add 25% whole rye flour for 3–4 feedings |
| Starter is too young | Keep feeding — days 3–5 often go quiet before taking off |
If it's still not rising after fixing all four, see our detailed sluggish sourdough starter fix. And check out our temperature control guide — cold is the killer most people miss.
Skip the guessing entirely — The Mother is a 288-year-old live culture that ships dehydrated and free with postage. Feed it twice and it passes the float test within 48 hours. No two-week build. No readiness anxiety.