A sourdough feeding ratio is three numbers — starter : flour : water — all measured by weight. A 1:1:1 ratio means equal parts of each; a 1:5:5 means five parts fresh flour and five parts water for every one part of old starter. The ratio is a timer you set with a scale: bigger numbers mean more fresh food per unit of old culture, which means a longer peak time.
According to King Arthur Baking’s feeding ratio trials, a healthy starter fed 1:1:1 at 78°F peaks in 4–6 hours; fed 1:4:4 it takes about 12 hours.
Peak Times at 75°F (24°C) by Ratio
| Ratio | Peak time | Best use |
|---|---|---|
| 1:1:1 | 4–6 hours | Same-day baking, twice-daily counter maintenance |
| 1:2:2 | 6–8 hours | Morning feed for late-afternoon bake |
| 1:3:3 | 8–10 hours | Warm kitchen, once-a-day feeding |
| 1:5:5 | 10–12 hours | Overnight feed before morning bake |
| 1:10:10 | 14–18 hours | Reviving a neglected starter; weekly fridge refresh |
Times shift with temperature. Warmer kitchens shorten every row by up to half; cooler kitchens stretch them. Measure your dough and kitchen temperature and adjust accordingly — or use the sourdough schedule calculator.
How Temperature Shifts the Peak
The same starter fed 1:5:5 will peak at very different times depending on where you keep it:
| Kitchen temp | Approximate peak time (1:5:5 ratio) |
|---|---|
| 65°F (18°C) | 14–20 hours |
| 70°F (21°C) | 12–15 hours |
| 75°F (24°C) | 10–12 hours |
| 78°F (26°C) | 8–10 hours |
| 80°F (27°C) | 6–9 hours |
If your kitchen is warm in summer, use a higher ratio (1:5:5 or 1:10:10) for the same overnight timing you’d get in a cooler kitchen with a 1:3:3.
What the Ratio Actually Does
Fresh flour and water dilute the acid that has built up in the old starter. At peak, a starter’s pH sits around 3.5–4.0 — acidic enough to inhibit the yeast and slow the rise. Adding fresh material lifts the pH back into the yeast’s active range (about 4.5–5.5), and the culture begins rising again.
A 1:1:1 feed dilutes the acid modestly; the mixture is one-third old starter from the start. A 1:5:5 feed dilutes far more — the old starter is only one-eleventh of the jar — so the culture has more generations to multiply through before the pH drops again. That is the mechanism behind the longer peak time.
How Much to Keep
Keep the smallest amount you can stand, typically 20–40 g. This minimizes flour waste and discard. If you need 200 g of ripe starter for a recipe, build it the night before from a small mother culture:
- Keep 20 g of mother starter
- Feed 1:5:5: add 100 g flour + 100 g water
- Total = 220 g, ready at peak in 10–12 hours at room temperature
- Use 200 g for baking; keep 20 g back as the next mother
What to Do With Discard
Every time you feed a starter, you remove some of the old culture before adding fresh flour and water. That removed portion is called discard. It is not bad — it is simply unfed starter that is past peak. It still contains active yeast and bacteria, just in a more acidic state.
Uses for discard:
- Pancakes and waffles: Discard adds tang and a slightly open texture. Replace up to half the flour in a pancake recipe with discard.
- Crackers: Discard mixed with flour, oil, and salt makes crispy crackers without any extra leavening.
- Pizza dough: Mix discard with a small amount of commercial yeast for a longer-fermented, more flavorful pizza dough.
- Quick breads: A few tablespoons of discard added to banana bread or muffin batter adds subtle complexity.
- Refrigerate and accumulate: Discard keeps in the fridge for up to 2 weeks. Collect it in a jar and use when you have enough for a batch.
Avoid using discard in recipes that require the starter to be at full activity and peak rise — discard won’t provide the same leavening as ripe, fed starter.
Choosing a Ratio by Your Schedule
Baking this afternoon: Feed 1:1:1 or 1:2:2 first thing in the morning.
Baking tomorrow morning: Feed 1:5:5 before bed (9–11 p.m.). It peaks overnight.
Baking in two days: Feed 1:5:5, let it peak, refrigerate. Pull it out the night before baking and give it one more feed.
Just maintaining the starter: Feed 1:5:5 once daily at room temperature, or refresh once a week in the refrigerator with a strong feed after warming up.
Fridge Versus Counter Storage
| Location | Temperature | Feed frequency | Ratio to use |
|---|---|---|---|
| Counter | 68–78°F | Once or twice daily | 1:1:1 or 1:2:2 |
| Refrigerator | 38–42°F | Once a week | 1:5:5 on takeout, then refrigerate |
Refrigerator starters need to warm up before baking. Pull the starter out 1–2 days before you plan to bake, discard most of it, and give it two or three room-temperature feeds to restore full activity.
Troubleshooting a Struggling Starter
Liquid on top (hooch). Gray or dark liquid pooling at the top means the starter ran out of food and the yeast produced alcohol as a byproduct. It is not ruined — pour off the liquid or stir it back in, discard most of the starter, and give it a larger feed (1:5:5 or 1:10:10) to reset. Hooch means you need to feed more often or at a higher ratio.
Starter rises but smells strongly of acetone or nail polish remover. Very high acetic acid production, often from infrequent feeding or cold storage. Feed more often at room temperature for 2–3 days to rebalance toward lactic acid (milder, yogurt-like flavor).
Starter doesn’t rise at all after feeding. Check: Did you use chlorinated tap water? Let water sit uncovered for 30 minutes before using, or use filtered water. Is the flour fresh and not bleached? Bleached flour can slow wild yeast activity. Is the kitchen colder than 65°F? Yeast becomes sluggish below that threshold. Move to a warmer spot.
Starter peaks and collapses faster than expected. Ratio is too small for the temperature. Increase to a higher ratio (1:5:5 instead of 1:2:2) so it has more food to work through before exhausting itself.
Rye or whole wheat accelerating too much. Whole grain flours carry more wild yeast and enzymes. If peak is happening too fast, reduce the whole grain percentage of your feeding flour to 10% or eliminate it temporarily.
What Ratio Does Not Change
The ratio sets peak timing, not baking performance. King Arthur’s trials show that starters fed at different ratios produce breads with the same rise and crumb once fed at the proper time relative to baking. A 1:5:5 starter at peak performs the same as a 1:1:1 starter at peak — the difference is only how long you wait.
Hydration Is Separate From Ratio
Keeping flour and water parts equal gives a 100%-hydration (liquid) starter. You can change hydration without changing timing: a 1:5:2.5 feed makes a 50%-hydration stiff starter. It rises slower and slightly more sour due to acetic acid favoring stiffer conditions. Most home bakers stick with 100% hydration for simplicity.
For how your fed starter fits into a full bake day, see sourdough schedule examples.