Enter your total starter amount, starter ratio, flour ratio, and water ratio into the Sourdough Starter Feeding Calculator to get the exact grams of starter, flour, and water needed for your next feeding. You can also select a timeframe to match how long until you plan to bake — the calculator outputs precise measurements so your starter peaks right on schedule.
Starter to Use
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Flour to Add
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Water to Add
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Hydration Level
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Feeding Ratio
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A feeding ratio describes how much existing starter, flour, and water you combine, expressed as parts (e.g. 1:1:1 means equal weights of starter, flour, and water). A higher flour and water ratio relative to starter (e.g. 1:5:5) produces a milder, slower-rising starter, while a 1:1:1 ratio ferments faster and is better for warmer environments.
A good rule of thumb is to make enough starter for your recipe plus a little extra to maintain your jar. Most bread recipes call for 50–200g of starter, so feeding to a total of 150–250g covers most needs while keeping waste low.
Most sourdough starters are kept at 100% hydration, meaning equal weights of flour and water (a 1:1 flour-to-water ratio). A stiffer starter (lower hydration, around 65–80%) ferments more slowly and has a milder flavor, while a wetter starter ferments faster and is easier to incorporate into doughs.
The time until you plan to use your starter determines which feeding ratio is most appropriate. If you need your starter active in 4–6 hours, a lower ratio like 1:1:1 works well at room temperature. For a 10–14 hour window, a larger ratio like 1:3:3 or 1:5:5 slows fermentation so your starter peaks just in time.
Yes! The weight-based ratios work the same regardless of flour type. Keep in mind that whole wheat and rye flours ferment faster than white flour due to higher enzyme and mineral content, so you may want to use a slightly larger ratio or cooler temperature to manage timing.
If kept at room temperature (around 75°F/24°C), most starters need feeding once or twice a day. If stored in the refrigerator, you can feed once a week. Always feed when your starter shows signs of falling — after it has peaked and begun to deflate — for the most active results.
Discard is the portion of starter you remove before feeding. This keeps your starter quantity manageable and prevents over-acidification. The discarded starter isn't wasted — it can be used in pancakes, crackers, waffles, and other recipes that benefit from a mild sourdough flavor.
Fermentation speed is heavily influenced by temperature. The 75°F (24°C) baseline is a common average for home kitchens and is the temperature at which standard timing guidelines are calibrated. If your home is warmer, your starter will peak sooner; if cooler, it will take longer — adjust your ratio or timing accordingly.