What does a 1-2-2 sourdough feeding ratio mean?

It means for every 1 part of starter you keep, you add 2 parts flour and 2 parts water by weight. So 50 g of starter is fed with 100 g flour and 100 g water, giving 250 g of starter at 100 percent hydration. A larger ratio like 1-5-5 dilutes the starter more and slows the rise, which is useful before a long fridge rest.

How much starter should I keep before feeding?

Most home bakers keep 20 to 50 g and discard the rest, because a small amount needs far less flour to maintain and still doubles reliably. Use target mode if you need a specific total for a recipe, and the calculator back-solves how much to keep so nothing is wasted.

Does the feeding ratio change the hydration?

The hydration of the fresh feed equals the water parts divided by the flour parts, so a 1-2-2 feed is 100 percent hydration. If you feed with more water than flour the starter becomes wetter and more active, and with less water it becomes a stiffer starter that ferments more slowly.

Why discard some starter each feed?

Without discarding, the amount doubles every feed and you would need ever more flour to keep it healthy. Removing most of the starter keeps the food-to-microbe ratio high so the culture stays vigorous, and the discard can go straight into pancakes, crackers or crumpets.

What is the Sourdough Starter Feeding Calculator?

Work out precisely how much flour and water to feed your sourdough starter for a 1-1-1, 1-2-2 or custom ratio, and the resulting hydration. Runs entirely in your browser. It runs free in your browser on Gera Tools, with nothing uploaded.

Sourdough Starter Feeding Calculator

Name: Sourdough Starter Feeding Calculator
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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Feed your starter by the numbers, not by guesswork

A sourdough starter is happiest on a predictable feed. The ratio you choose — written as starter to flour to water — controls both how much your culture grows and how fast it ferments. A warm-kitchen 1-1-1 feed peaks in a few hours, while a 1-5-5 feed stretches the rise out for an overnight or fridge schedule. This calculator turns whichever ratio you pick into exact gram weights, so every feed is repeatable.

How the maths works

Everything is a simple multiple of the starter you keep. For a ratio of 1 to F to W, the flour added is your kept starter times F and the water added is your kept starter times W. The total after feeding is the sum of all three, and the hydration of the fresh feed is the water parts divided by the flour parts. There is no lookup table and nothing is sent to a server — it is pure arithmetic on the numbers you enter, which makes it safe and instant.

Keep mode versus target mode

Use keep mode when you maintain a fixed amount of starter and just want to know what to add. Switch to target mode on baking day, when you know you need, say, 300 g of ripe starter for a recipe and want the calculator to work backwards to how much to keep and feed. Either way you get the flour, the water and the total in grams, plus a reminder to discard down to the kept amount before you feed.