Multiply every ingredient by the same scale factor. Check the target as mixed dough weight, then make a separate plan for bowls, proofing space and baking.
- Divide target batch weight by original batch weight.
- Scale starter, salt and inclusions consistently.
- Larger batches can change handling and timing even when proportions stay the same.
Scaling means changing size while preserving ratios
To scale a sourdough recipe, multiply every ingredient weight by the same factor. If the flour doubles while water, starter, and salt stay unchanged, you have designed a different dough rather than made a larger batch of the original. A consistent factor preserves the ingredient relationships, provided the starter has the same hydration as before.
King Arthur Baking’s baker’s percentage reference explains how flour-based ratios support recipe conversion. This guide applies that arithmetic to sourdough with original worked examples. Ingredient scaling is exact within the accuracy of the inputs; fermentation schedules, mixer behavior, and baking times do not scale with the same factor. Keep those process decisions separate from the weight calculation.
Choose the right starting recipe
Begin with a complete mixing list in weights, including starter, salt, and any water added later. A useful example contains 450 g fresh flour, 310 g fresh water, 100 g starter at 100% hydration, and 10 g salt. Its mixed dough weight is 870 g. The starter contributes 50 g flour and 50 g water, giving 500 g total flour and 360 g total water.
The total formula is therefore 72% hydration, 2% salt, and 10% prefermented flour. Starter mass is 20% of total flour. These labels make the example easier to audit after resizing. If the original recipe measures starter only by volume or omits its hydration, establish a weight and an explicit assumption before claiming an exact conversion.
Use one factor for the whole mixing list
Scaling factor = target mixed dough weight ÷ original mixed dough weight. To increase the example from 870 g to 1,305 g, divide 1,305 by 870 to get 1.5. Multiply each ingredient by 1.5: fresh flour becomes 675 g, water 465 g, starter 150 g, and salt 15 g.
The new list adds to 1,305 g. Its starter contributes 75 g flour and 75 g water, so total flour is 750 g and water is 540 g. Dividing 540 by 750 confirms 72% hydration; dividing 15 by 750 confirms 2% salt. A reverse check is especially useful when a spreadsheet or calculator has several similar fields and you want to confirm that each received the same multiplier.
| Ingredient | Original batch | 1.5 times | 2 times |
|---|---|---|---|
| Fresh flour | 450 g | 675 g | 900 g |
| Fresh water | 310 g | 465 g | 620 g |
| 100% hydration starter | 100 g | 150 g | 200 g |
| Salt | 10 g | 15 g | 20 g |
| Mixed dough | 870 g | 1,305 g | 1,740 g |
Plan portions from mixed dough weight
If you want three equal dough pieces of 435 g, the 1,305 g batch supplies exactly that theoretical total. These are raw dough weights, not promised finished loaf weights. Dough left on tools, containers, and the work surface reduces the amount available for dividing, and baking changes the mass further.
Decide whether your portion target allows for ordinary handling loss. If it does not, add a clearly labeled production allowance based on your own measured process, then scale the entire formula to that larger batch. Do not quietly add extra flour alone as an allowance. That changes hydration and salt percentage instead of simply giving you slightly more dough to divide.
Work from a target flour quantity
Sometimes flour availability determines the batch size. The example uses 500 g total flour. If you want to use 800 g total flour, the factor is 800 ÷ 500 = 1.6. The mixing list becomes 720 g fresh flour, 496 g fresh water, 160 g starter, and 16 g salt, giving 1,392 g dough.
Notice that 800 g total flour is not the same as 800 g fresh flour. The starter already contains 80 g of the total. If you have precisely 800 g fresh flour available and want to preserve the original formula, use 800 ÷ 450 as the factor instead. The distinction changes the batch size substantially enough that a calculator should label the flour field unambiguously.
Convert a total formula into a dough target
A lean dough at 72% hydration and 2% salt has a total formula multiplier of 1.74. Divide desired mixed dough weight by 1.74 to get total flour. For 1,740 g dough, the result is 1,000 g flour; total water is 720 g and salt is 20 g.
At 10% prefermented flour and 100% starter hydration, 100 g flour and 100 g water are carried inside 200 g starter. Subtract them from the totals to obtain 900 g fresh flour and 620 g fresh water. Adding those amounts with the starter and salt returns 1,740 g. Do not add starter percentage again to the multiplier because its flour and water have already been counted.
When the target produces awkward decimals
Not every batch size divides neatly. For 1,000 g dough at the same formula, total flour is approximately 574.713 g, water 413.793 g, and salt 11.494 g. At 10% prefermented flour, the starter is approximately 114.943 g; fresh flour is 517.241 g and fresh water is 356.322 g.
A practical mixing list might be 517 g fresh flour, 356 g water, 115 g starter, and 11.5 g salt, totaling 999.5 g. It is better to show this small rounding difference than to disguise it. If a scale reads only whole grams, choose a sensible rounding policy and recalculate the achieved formula. Do not round all intermediate values before determining the final ingredient list.
Scaling when starter is the limiting ingredient
If you have 80 g usable starter and the original recipe requires 100 g, a factor of 0.8 preserves the formula. Weigh 360 g fresh flour, 248 g water, 80 g starter, and 8 g salt. The result is 696 g dough containing 400 g total flour and 288 g water.
Usable starter means the amount available for the dough after retaining whatever you plan to maintain separately. If the jar holds 80 g and you intend to keep 20 g, only 60 g is available for this calculation. Alternatively, build more starter before mixing. Reducing starter without reducing the other ingredients is a legitimate formula change, but it is not the same operation as scaling the recipe.
Keep starter hydration consistent
Multiplying the original 100 g starter by two assumes that the resulting 200 g starter has the same flour-water composition. Replacing it with 200 g of a 60% hydration starter changes the flour and water contributions. The stiffer starter contains 125 g flour and 75 g water, instead of 100 g of each.
To preserve the doubled dough’s total flour and water, subtract the actual starter components from the totals. For 1,000 g total flour and 720 g water, use 875 g fresh flour and 645 g fresh water with that 200 g stiff starter. The overall hydration remains 72%, but prefermented flour rises to 12.5%. Preserving that percentage too requires selecting a different starter weight, not merely correcting the water.
Scaling multiple flours and additions
Apply the same factor separately to each flour in a blend. If a mixing list contains bread flour and whole wheat flour, combining them into one number before scaling can hide the intended proportions. Remember that the starter flour also belongs somewhere in the total blend, especially if you are comparing whole grain percentages across recipes.
Additional ingredients should scale too, unless you intentionally change the formula. If the 870 g example receives an extra 50 g dry seeds, its new mixed mass is 920 g. To scale that entire seeded recipe to 1,840 g, double all ingredients including the seeds. Using 870 g as the denominator after adding seeds would calculate a batch larger than intended. Soaked inclusions also require a clear account of retained water.
Mixer and container capacity are separate checks
A mathematically correct batch may be too large for the mixer or too small for its dough hook to engage effectively. King Arthur Baking’s guidance on reducing recipes notes that small dough batches may need hand mixing. Check the equipment’s documented capacity and leave adequate space in fermentation containers before committing to a larger mix.
Container geometry also changes what you can observe. A broad bowl and a narrow container show expansion differently. When repeating a recipe at another scale, record the container and watch the dough rather than treating the original marked height as a universal endpoint. These are practical process checks; the ingredient multiplier alone cannot establish the best equipment arrangement for your batch.
Do not multiply fermentation or baking time
Doubling ingredients does not mean doubling bulk fermentation, proofing, or baking time. Dough condition, temperature, starter activity, loaf shape, and equipment all matter. King Arthur Baking’s recipe-reduction guidance emphasizes using the recipe’s visual cues rather than relying exclusively on its listed proofing time after a batch-size change.
Separate the total batch from the size of each loaf. If you double a recipe and still divide it into pieces of the original size, each piece has not doubled. If you combine the entire batch into one larger loaf, its baking behavior changes more substantially. A calculator can produce the division weights, but it should not claim a precise new baking schedule from weight alone.
Plan the work as well as the ingredients
Four loaves may fit in your mixing bowl while only one fits in your covered baking vessel. That creates a scheduling constraint after shaping. Before enlarging a batch, decide how the dough pieces will be held and baked using a method appropriate to the recipe. A convenient total dough weight is only one part of a workable baking session.
Similarly, more dough can require more time to divide and shape. Keep track of the order in which pieces are handled instead of assuming every loaf has experienced identical conditions. If the practical workflow becomes difficult, several smaller batches may be easier to manage. That is an equipment and scheduling decision, not evidence that baker’s percentage stopped working.
Record theoretical and actual yield separately
Theoretical yield is the sum of the ingredients that enter the dough. Actual divided yield is what you weigh into portions. Finished yield is what remains after baking and cooling. Keep those three measurements in separate columns if you want to understand where differences occur. Do not label a 900 g dough piece as a guaranteed 900 g baked loaf.
You can estimate future yield from your own repeated measurements, but label any allowance as an estimate. For example, if a particular process previously returned 980 g divisible dough from a 1,000 g mix, that observation describes that process and occasion. It is not a universal loss rate. Preserve the original formula, target size, rounded mixing list, and actual portions so the next scaling decision rests on a clear record.
Sources & further reading
This guide combines published references with our own explanations and decision aids. Numerical examples are illustrative; they are not records of Sourdough Bench test bakes.
Put it into practice.
Keep the recipe, observations and next change together in your downloadable bake log. For a symptom-led starting point, use the loaf troubleshooting guide.