Sourdough starter calculator
A sourdough feed is a ratio of starter : flour : water — 1:1:1 peaks fast, 1:5:5 peaks slower and stays sweeter. Set how much you keep and how big a feed, and the flour, water and peak time fall out.
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.
How do sourdough starter feeding ratios work?
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 LoafMath hydration solver will count that starter correctly when you build your dough.
Sourdough starter feeding ratio chart: peak times
Hours until a 100% hydration starter peaks, by feed ratio and kitchen temperature. These come from the same estimate the calculator uses, so treat each one as a window, not a promise.
| Feed ratio | 20 °C (68 °F) | 24 °C (75 °F) | 28 °C (82 °F) |
|---|---|---|---|
| 1:1:1 | 4–7 h | 3–5 h | 2–4 h |
| 1:2:2 | 7–11 h | 5–8 h | 3–6 h |
| 1:3:3 | 9–15 h | 6–11 h | 5–8 h |
| 1:5:5 | 14–23 h | 10–16 h | 7–11 h |
| 1:10:10 | 25–42 h | 18–30 h | 13–21 h |
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.
What feeding ratio should I use overnight or the night before baking?
Pick the feed that peaks when you wake up. In a cool 20 °C kitchen, 1:2:2 peaks in about 7–11 hours and 1:3:3 in about 9–15 hours, which suits a 10 pm feed for a morning bake. If you need it to wait a whole day, 1:5:5 takes about 14–23 hours. Warmer kitchens are faster, so set your temperature above and the calculator gives the window for your exact feed.
How do I feed a sourdough starter kept in the fridge?
A fridge starter needs far less attention: most bakers feed it about once a week (King Arthur Baking’s guidance). Before it goes in, give it a normal feed and let it start rising for an hour or two. To wake it for baking, take it out and give it one or two room-temperature feeds until it rises predictably again. The peak times on this page assume a room-temperature starter, so the first feed out of the fridge will usually be slower.
Can I feed my starter using cups instead of grams?
You can, but the ratio stops being accurate. Feeding ratios are by weight, and a cup of flour weighs about 120 g (King Arthur Baking’s chart) while a cup of water weighs about 236 g. So equal weights of flour and water are roughly 1 cup flour to ½ cup water, not a cup of each. How you scoop changes a cup of flour a lot, so a cheap kitchen scale gives a far more reliable starter.
How much starter should I keep, and how much should I discard?
Keep only what your feed needs. If you feed 1:5:5 and want about 110 g of ripe starter, you only need to keep 10 g, so everything else is discard. Keeping a small amount and feeding a big ratio wastes less flour than keeping a lot and feeding 1:1:1. Enter the amount you keep above and the calculator shows the flour and water to add and the total you will end up with.