Sourdough Starter Calculator

Enter your current starter weight and your desired final starter weight after feeding. Set your target starter hydration (100% = equal flour and water). The calculator outputs exactly how much flour and water to add to hit your target weight at your target hydration.

Common feeding ratios are 1:1:1 (starter:flour:water by weight) for daily maintenance, or 1:5:5 for a long overnight rise. A higher ratio of fresh flour to starter slows fermentation and is useful if you are not baking every day. Use the calculator to work backward from any target weight.

A standard sourdough loaf uses roughly 100–150g of active starter (20% of flour weight for a 500g flour recipe). Build your starter to at least 50g more than you need; always hold a little back as insurance.

A 100% hydration starter is fed with equal weights of flour and water. It has a thick pancake-batter consistency, is easy to stir, and is very active. Most home baker recipes assume 100% hydration unless stated otherwise.

A stiff starter (50–65% hydration) is firmer, rises more slowly, and tends to produce a milder, less acidic flavor. It is used in some Italian breads (like Panettone) and by bakers who prefer a sweeter sourdough flavor profile. Stiff starters are harder to stir but easier to shape.

Work backward from how much starter you need. If your recipe needs 200g, start 1–2 days before and build in stages. For example: Day 1 evening, feed 20g starter with 40g flour and 40g water (get 100g). Day 2 morning, feed all 100g with 50g flour and 50g water (get 200g). The calculator handles each stage.

Decide on the target hydration (e.g., 60%). Take a small amount of your liquid starter and feed it with more flour than water in the ratio needed to hit 60%. Repeat for 2–3 feedings until the culture adapts. The starter calculator can show you the flour/water split for any hydration target.

Yes. The calculator saves your recent feedings in browser local storage so you can see when you last fed, what ratio you used, and how your starter has been performing. This history is stored only in your browser and never sent to a server.

Discard is the portion of starter you remove before each feeding to keep the total volume manageable. Without discarding, you would need exponentially more flour each day. Many bakers use discard in pancakes, crackers, or waffles. The calculator shows how much to discard to hit your target weight after feeding.