Sourdough starter ratio calculator
Tell it how much starter your recipe needs and how you like to feed. It returns the grams to mix and roughly when it will peak.
Feeding ratio (starter : flour : water)
- Starter
- 21g
- Flour
- 105g
- Water
- 105g
Makes 230 g at 100% hydration. Use 200 g, keep 30 g for next time.
Expected peak
9–12 hours
A rough guide for a healthy, regularly fed starter. Watch the jar, not the clock: it’s ready when it has roughly doubled, is domed and full of bubbles.
Why a bigger feed buys you time
Each feed dilutes the hungry yeast and bacteria with fresh flour. The more food per gram of old starter, the longer the colony needs to eat through it. Step through the ratios.
33% old culture
At 1:1:1 every gram of culture gets 2 g of flour and water to work through. Peaks fast; handy in a cool kitchen.
How starter feeding ratios work
A ratio is written starter : flour : water, by weight. The flour and water numbers set the hydration (equal parts make a 100% starter), and the first number decides how much of the old, acidic culture carries into the new batch. Less carry-over means a slower rise and a milder, less vinegary levain.
After a feed, a healthy starter rises, domes, then slowly sinks back, and that daily swell-and-fall is the best clock you have. It waxes and wanes like a small Moon in a jar; for the real one, ahaboo’s interactive take on lunar phases shows what is actually changing.
Common schedules
| Ratio | Peak at ~24 °C | Good for |
|---|---|---|
| 1:1:1 | 4–6 h | Cool kitchens, quick top-ups |
| 1:2:2 | 6–8 h | Morning feed, afternoon mix |
| 1:5:5 | 9–12 h | Overnight levain |
| 1:10:10 | 12–14 h | Warm summers, mild flavour |
Once the levain is ready, plug it into the sourdough calculator so its flour and water are counted in the dough.
Questions bakers ask
What does a 1:1:1 starter ratio mean?
One part existing starter, one part flour, one part water, by weight. 50 g starter + 50 g flour + 50 g water gives 150 g of starter at 100% hydration.
Which feeding ratio should I use?
Use 1:1:1 in a cool kitchen or when you need starter in 3–5 hours. 1:2:2 or 1:3:3 suits a 6–8 hour rhythm. 1:5:5 to 1:10:10 slows the starter down for an overnight or 12-hour feed, and reduces sourness because less acidic old culture carries over.
How do I make exactly the amount of starter a recipe needs?
Enter the target (for example the 200 g levain in your recipe) plus a little extra to keep, choose a ratio, and the calculator splits it into starter, flour and water. Keeping 20–30 g back means you never use up the culture.
How long until a starter peaks?
At about 24–26 °C a healthy 100% hydration starter typically peaks around 4–6 hours after a 1:1:1 feed, 6–8 hours at 1:2:2, and 10–12 hours at 1:5:5. Every 2–3 °C cooler adds roughly an hour or two.
Can I change my starter’s hydration?
Yes. Set flour and water separately (for example 1:2:1 gives a stiff 50% starter). Stiffer starters ferment more slowly and lean towards acetic sourness; the ratio fields accept any numbers.