Sourdough starter feeding calculator for precise ratios and hydration

Calculate sourdough starter feeding plan

Choose a ratio (seed:flour:water), set your final amount, and enter how much starter you have now. The result shows exactly what to keep, what to add, hydration, and suggested discard.

Select a preset or set custom parts, then enter your final amount and current starter to see exact feed amounts.

Sourdough starter feeding calculator quick guide and timing tips

This sourdough starter feeding calculator for precise ratios and hydration turns any ratio into a clear shopping-list style plan. Choose a preset like 1:2:2 for a predictable rise, or use Custom parts to match a recipe. Set a final amount that covers the levain you need plus a small reserve to keep feeding.

The numbers are parts by weight. With 1:2:2, every gram of seed gets two grams of flour and two grams of water—100% hydration. Bigger feeds like 1:5:5 slow things down (good for warm kitchens). Smaller feeds like 1:1:1 peak sooner (good when you’re on a schedule).

  • Target enough for the bake and a spoonful to save as your next seed.
  • Use a scale—weights are consistent, scoops aren’t.
  • Assumes seed ~100% hydration; change only if you keep a different routine.

After you calculate, the summary shows Seed to keep, Flour to add, Water to add, your hydration, and any discard if you currently have more starter than the seed mass required. Want zero discard? Lower the final amount or use a higher parts ratio so seed is a smaller share.

How the sourdough feeding math works

For a ratio a:b:c (seed:flour:water), total parts are a+b+c. Final amount × a/parts = seed mass, × b/parts = flour mass, × c/parts = water mass. Hydration is (water ÷ flour) × 100. If your on-hand starter is greater than the seed mass, the extra is suggested discard before feeding; if it’s less, build in stages or reduce your final amount.

Common sourdough feeding questions
Can I switch to whole grain or rye for feeds?

Yes. Fermentation runs a bit faster and the texture thickens. Keep the parts the same and watch peak timing.

What if my kitchen is very warm?

Use a larger ratio like 1:4:4 or 1:5:5, keep the jar cooler, or refrigerate between feeds to avoid overproofing.

How do I scale for a big levain build?

Increase the final amount and choose 1:2:2 or 1:3:3. Give enough time for the levain to dome and hold before mixing.

References and further reading