Sourdough starter calculator
Keep a little starter, feed it by ratio, and know roughly when it will peak. Set how much you keep and how big a feed — the flour and water fall out, and you get a peak-time estimate for your kitchen.
Ratio is starter : flour : water, by weight.
- Peak-time is a guide — warmer kitchens rise faster, cooler ones slower.
- A bigger feed (1:5:5) peaks later and keeps the starter sweeter.
Ratios, timing and temperature
A feed ratio reads starter : flour : water. Keep one part of your existing starter, then add that many parts of flour and water. 1:1:1 keeps 50 g and adds 50 g of each; 1:5:5 keeps 50 g and adds 250 g of each. The bigger the feed, the more food the yeast has to work through — so it peaks later and stays pleasant for longer before it turns sharp and falls.
How temperature changes the clock
Temperature is the other big lever. A starter that peaks in six hours at a cool 20 °C might peak in under four at a warm 28 °C — roughly halving for every 8 °C warmer. The estimate above bakes that in, but treat it as a window, not a stopwatch: watch for the starter to roughly double, dome, and just begin to recede. That is peak, and that is when it is strongest for mixing dough.
Keeping hydration where you want it
Feeding with equal flour and water keeps a 100% starter at 100%. Want a stiffer starter for more sourness and staying power? Feed more flour than water — the calculator shows the resulting hydration so you can dial it in. Whatever you choose, the DoughMath hydration solver will count that starter correctly when you build your dough.
Starter feeding FAQ
What is the best feeding ratio for sourdough starter?
There is no single best ratio — it depends on your schedule. A 1:1:1 feed peaks fast (good if you bake the same day); 1:3:3 or 1:5:5 peaks slowly (good for overnight, or to build a bigger levain). Bigger feeds also keep the starter sweeter for longer. Pick the ratio that peaks when you want to use it.
Should I feed my starter 1:1:1 or 1:2:2?
1:1:1 (equal parts) peaks in roughly 4–6 hours at room temperature — handy for same-day baking but it also sours and collapses sooner. 1:2:2 gives the starter more food, so it peaks a couple of hours later and holds its peak longer. Use 1:1:1 when you are in a hurry, 1:2:2 when you want a wider window.
What is the 1/3/3 rule for sourdough starter?
It is shorthand for a 1:3:3 feed — one part starter to three parts flour to three parts water by weight. So 30 g of starter gets 90 g flour and 90 g water. It is a popular maintenance feed because it peaks in a convenient 8–10 hours at room temperature and keeps the starter healthy between bakes.
How much to feed 50g of sourdough starter?
That depends on the ratio. Keeping 50 g and feeding 1:5:5 means adding 250 g flour and 250 g water for 550 g total. A gentler 1:1:1 adds just 50 g of each. Set your keep amount and ratio above and the calculator gives you the exact grams.