Sourdough starter feeding ratios, explained

What a feeding ratio actually tells you

A sourdough feeding ratio describes the weights you combine at one refreshment. Sourdough Bench always writes the order as seed starter : fresh flour : fresh water. A 1:4:4 feed therefore uses one part existing starter, four parts flour, and four parts water. The numbers are proportions, not grams until you choose a batch size. They also do not tell you how many hours the mixture will need before baking. Keep those two questions separate: the ratio determines an ingredient build; observation determines when that build is useful.

For example, 15g seed with 60g flour and 60g water is a 1:4:4 feed weighing 135g. So is 25g seed with 100g flour and 100g water, weighing 225g. The larger jar does not contain a stronger ratio. It contains more of the same mixture. This distinction helps when you want to reduce everyday maintenance quantities without changing the relationship between old starter and its new food. Always record the actual grams alongside the shorthand.

Read the order before comparing two instructions

Some recipes list their ingredients as starter, water, flour. Others put flour first. Equal feeds hide that difference because 1:1:1 looks identical whichever ingredient comes second. Unequal feeds do not. If a stiff build is written as 1:2:1, you need to know whether the last number means water or flour before using it. Write the ingredient names out the first time you follow a new method, especially when moving numbers between a recipe and a calculator.

Parts should use a common unit of mass. Do not measure one part starter in cups, another part flour in grams, and another part water in tablespoons. That combines different quantities into something that is no longer a ratio. A scale also avoids treating an aerated cup of ripe starter as equivalent to the same cup after stirring. King Arthur's maintenance guidance recommends weighing starter because its volume changes with consistency and trapped gas. The useful habit is simple: tare the vessel, weigh the retained seed, then weigh each addition.

Compare ratios at the same total weight

For a 180g build, a 1:1:1 feed contains 60g seed, 60g flour, and 60g water. At 1:2:2, the same total contains 36g seed and 72g each flour and water. At 1:4:4, it contains 20g seed and 80g each flour and water. These examples hold the total constant so the difference is visible: increasing the flour and water parts reduces the share of existing starter in the new mixture.

Under otherwise similar conditions, changing that share can change the progression of fermentation. King Arthur's published feeding comparison illustrates that larger refreshments can take longer to reach their greatest rise. Its observed timings describe its starter and conditions, not a schedule guaranteed in another kitchen. Flour choice, temperature, the condition of the seed, and the point at which you observe the jar also matter. Use a ratio as a setting you can record and compare, rather than attaching a universal clock time to it.

Do not confuse feeding parts with baker’s percentages

A feeding ratio uses the existing starter as one named ingredient. A dough formula expressed in overall baker’s percentages uses total flour as its reference. These are different descriptions, so a 1:4:4 feed does not mean a dough contains 25% prefermented flour. To calculate that dough percentage, you need the flour contained in the levain and the flour in the complete dough. For example, 200g of 100% hydration levain contributes 100g flour. If the complete dough contains 500g total flour, 20% of its flour arrived through the levain. Keep that calculation separate from the ratio used to prepare the levain, and label which percentage you mean when sharing a formula.

Scale a ratio with one short calculation

Add the ratio parts first. For 1:4:4, the total is nine parts. Divide the amount of starter you want after mixing by nine to find the seed amount; multiply that seed amount by four for each addition. In general, for a ratio a:b:c and a desired mixed mass M, seed is M × a ÷ (a+b+c), flour is M × b ÷ (a+b+c), and water is M × c ÷ (a+b+c). All three answers use the same mass unit as M.

Suppose your dough needs 200g levain and you want 20g left to maintain. The planned build is 220g. At 1:4:4, the calculated weights are 24.444g seed, 97.778g flour, and 97.778g water, totaling 220g after rounding to three decimals. A normal kitchen scale does not need to reproduce every decimal. You could weigh 24g seed and 98g each flour and water to total 220g, while recognizing that the rounded ratio is approximately 1:4.08:4.08. Record what you actually weighed.

A reserve is an allocation, not another ingredient

The 20g reserve in that example is already inside the 220g total. Do not build 220g and then add another 20g seed unless you deliberately mean to change the batch. When the build is suitable for the recipe, weigh 200g into the dough and retain the planned portion. Allow separately for residue if your transfer method routinely leaves starter on the jar and spoon; a calculated total is not a promise that every gram will reach its destination.

You can also keep a separate maintenance jar and build only the levain required for baking. That is a different arrangement with the same arithmetic. If the recipe needs 200g and your maintenance culture remains elsewhere, enter 200g as the build target instead of adding an unnecessary reserve. Choose one arrangement before feeding so you know which jar will continue your starter and which mixture is intended for the dough.

Why equal flour and water do not always mean 100% hydration

Hydration is water mass divided by flour mass, multiplied by 100. Existing seed already contains both ingredients. If that seed is at 100% hydration, equal fresh flour and water preserve 100% hydration. Thus 20g of that seed contains 10g flour and 10g water. Adding 80g of each gives 90g total flour and 90g total water, so the finished 180g build is at 100% hydration.

Now begin with 30g seed at 50% hydration. It contains 20g flour and 10g water. Adding 30g flour and 30g water gives 50g total flour and 40g total water: 80% hydration, despite an equal fresh feed. This is an ingredient accounting result, not an opinion about whether the culture will work. Recipes that assume a liquid, equal-flour-and-water starter need that assumption checked when your maintained culture is stiff or unusually wet.

Use the general hydration formula when needed

Let S be seed weight, F be added flour, W be added water, and h be the seed hydration as a decimal. For example, 100% becomes 1 and 50% becomes 0.5. Seed flour is S ÷ (1+h), and seed water is S × h ÷ (1+h). Final hydration is 100 × [W + S × h ÷ (1+h)] ÷ [F + S ÷ (1+h)]. The formula assumes the seed is modeled as flour and water; it does not account for other ingredients or fermentation losses.

You can use the same accounting to design a conversion. To combine 30g of 50% hydration seed with 60g fresh flour and finish at 100% hydration, total flour will be 80g. The seed contributes 10g water, so add 70g water. The mixed total is 160g. This does not preserve an equal-feed ratio, and it should not: you are deliberately correcting the starting imbalance. Label the new hydration instead of continuing to describe the mixture by its old maintenance routine.

Choose a useful experiment instead of chasing an ideal ratio

If your present feeding routine is dependable, first write down why you want to change it. Perhaps you need a smaller batch, want the levain ready later, or need a different hydration for a recipe. Only the first of those goals is solved by scaling weights alone. For a timing question, keep the flour blend, location, container, and seed condition as consistent as practical, and change one feeding ratio. Mark the starting level and observe how the new build develops.

The comparison becomes much less useful if you simultaneously move the jar to a warmer spot, switch flour, and use seed at a different stage. If several changes are necessary, record them without trying to identify a single cause afterward. A kitchen note such as 'different flour and warmer room; not comparable' is more informative than a confident conclusion that 1:4:4 is always faster or slower. A small, repeatable routine is enough; elaborate experiments are optional.

Handle rounding and small amounts honestly

Scale resolution matters more when the seed amount is tiny. A one-gram difference in 5g seed is a larger proportional change than a one-gram difference in 50g. If a planned build asks you to weigh less than your scale can measure reliably, increase the batch to a manageable size or use a suitable scale. Avoid implying precision by copying a long decimal answer into a jar weighed on a coarse scale.

Round the additions deliberately and check their sum. For a 150g 1:2:2 build, the values are exactly 30g, 60g, and 60g. For 200g at 1:4:4, they are recurring decimals, so an approximate practical version is 22g, 89g, and 89g. Both examples preserve a useful total; the latter only approximates the requested ratio. This small distinction keeps the calculator output clear without making normal home baking unnecessarily rigid.

What to write on the jar

A useful label includes the date and feeding time, seed weight, added flour and water, flour blend, and starting level. Include seed hydration when it differs from the routine assumed by your recipe. Leave enough space for expansion and use an appropriate food container. A label saying only '1:4:4' is incomplete when someone else cannot tell whether the build contains 90g or 450g, or whether it is intended as a levain or a maintenance refreshment.

Before mixing dough, check both quantity and condition. Correct arithmetic can produce exactly the amount you requested while the starter is still developing, has already fallen, or has an inconsistent feeding history. The feeding calculator answers the weighing question. Your recipe, the observed rise pattern, and your previous notes answer the readiness question. Keep those records together and the ratio becomes a practical tool for planning your next bake.