How much starter, flour and water to feed
A feeding ratio of 1:2:2 means one part ripe starter, two parts flour and two parts water, all by weight. The ratio decides how quickly the starter peaks, and the amounts decide whether you end up with enough levain for the loaf. This sourdough starter feeding calculator turns both into grams: tell it how much fed starter or levain the recipe needs (and how much to keep back), or how much starter you have, and it gives the starter, flour and water to mix.
It also estimates the time to peak, when the starter is at its highest and most active, from the ratio and the room temperature. The same amount is shown for every common ratio, so you can pick the one that peaks when you need it. Everything runs in your browser.
How to use the Sourdough Starter Feeding Calculator
- Choose whether you need a set amount of levain or want to feed the starter you have.
- Enter the amount in grams. For a recipe, add a little to keep back so the jar is never empty.
- Pick the feeding ratio: 1:1:1 for a fast daily feed, 1:5:5 or 1:10:10 for a slower feed that peaks overnight.
- Set the room temperature, then weigh the starter, flour and water into a clean jar, stir and note the time.
- Use the starter or levain once it has domed, is full of bubbles and has started to settle, within the time range shown.
Sourdough Starter Feeding Calculator features
Sized to your recipe
Enter the levain you need plus what to keep back and get the exact mix.
Six ratios side by side
1:1:1 to 1:10:10 for the same amount, with the time to peak for each.
Stiff starters too
Feed with 100, 75, 60 or 50 per cent water for a liquid or stiff starter.
Time to peak
A range for your room temperature in °C or °F, using the same model as the sourdough schedule planner.
How the mix is calculated
For a ratio of 1:r:r with equal weights of flour and water, the fed starter weighs starter × (1 + 2r). To end up with 170 g at 1:2:2 you need 170 ÷ 5 = 34 g of starter, 68 g of flour and 68 g of water. For a stiffer feed, the water is the chosen percentage of the new flour: at 50 per cent, 20 g of starter at 1:2:2 takes 40 g of flour and 20 g of water.
In a feed made with more flour and water, the old starter is more diluted, so the yeast and bacteria have more to eat and take longer to reach their peak. A 1:1:1 feed at 24 °C (75 °F) peaks in about five hours in this model, a 1:2:2 feed in about six, 1:5:5 in about eight and 1:10:10 in about eleven. A 10 °C drop roughly doubles the time. Real starters vary with the flour, the culture and its age, so the range here is a guide, not a promise.
Choosing a ratio
- 1:1:1 for a fast turnaround on a warm counter or to revive a sluggish starter. It needs feeding every few hours when it is hot.
- 1:2:2 to 1:3:3 for a twice-daily routine, or to build a levain in the morning for an afternoon mix.
- 1:5:5 to 1:10:10 to peak overnight or while you are at work, and in a warm kitchen to avoid over-ripening.
- Stiff starters (about 50 per cent water) are slower, less sour and ferment gently, which many bakers like for enriched doughs.
Starter, levain and what to do next
A levain is simply a portion of starter built up for one bake. Once it has peaked, the amount your recipe needs goes into the dough; to see that share against the total flour use the baker’s percentage calculator, and to plan the whole day, the sourdough schedule calculator works backwards from when you want to bake. Baking pizza? The pizza dough calculator sizes the dough balls. If the dough runs cold or hot, the dough temperature calculator gives the water temperature.
Sourdough Starter Feeding Calculator FAQ
What does a 1:2:2 starter ratio mean?
One part of ripe starter, two parts of flour and two parts of water by weight. For example 20 g starter, 40 g flour and 40 g water. The starter makes up one fifth of the mix.
What is the difference between 1:1:1 and 1:5:5?
In a 1:1:1 feed the old starter is a third of the mix, so it peaks quickly, in about five hours at 24 °C. In 1:5:5 it is under a tenth, so it peaks much later, in about eight hours, which suits an overnight feed.
How much starter do I need to keep?
As little as 10 to 20 g is enough to restart a jar, but a larger jar is easier to feed accurately. Keep-back adds that amount on top of what your recipe needs.
How long does a starter take to peak?
Usually four to twelve hours at room temperature, depending on the ratio, temperature and flour. Watch for a domed top and bubbles, not just the clock.
Do I have to discard starter?
Only to keep the amount manageable. Using the discard in pancakes or crackers is fine, and the calculator lets you size the feed so you throw away little.
Is the time to peak exact?
No. It is an estimate for a healthy starter, shown as a range. Warm rooms, whole-grain flour and a mature culture shorten it, and cool rooms lengthen it.