Sourdough scales by percentage like any bread, but the starter has to scale with it: the levain is built the night before, sized to the run, so it's at its peak when the dough is mixed. Then divide by weight, shape every loaf the same, proof overnight in the cooler, and bake full deck oven loads from cold. Done this way, a micro bakery that baked 6 loaves in a home oven bakes 120 a day from a shared kitchen's deck oven, and the cost of a loaf falls from $6.39 to $3.00. Below is the dough at three sizes, the steps, the bake loss, what a loaf costs at each size, and a free scaling calculator.
The short version
- Write the dough, levain included, as percentages; bakers also read it against the flour.
- Build the levain the night before, sized to the run.
- Divide by weight: about 1.75 pounds of dough for a 1.5-pound loaf.
- Proof shaped loaves overnight in the cooler.
- Bake full deck oven loads from cold, with steam.
- Weigh a few loaves before and after to know your bake loss.
- TaroStack keeps the recipe by weight, takes each batch's ingredients off stock and checks its yield. More below.
The recipe, by percentage
Prairie Hearth Bread, the made-up micro bakery in Fargo, North Dakota, I use in these examples, baked 6 loaves at a time at home, then rented time on a shared kitchen's deck oven. Its country loaf, weighed:
| Ingredient | % of the mix | Kitchen batch, 10.6 lb | One batch, 80 lb | The run, 212 lb | Cost a lb, bought in bulk |
|---|---|---|---|---|---|
| Bread flour | 47% | 4.98 lb | 37.6 lb | 99.6 lb | $0.45 |
| Water | 36.9% | 3.91 lb | 29.5 lb | 78.2 lb | $0.00 |
| Levain, half flour and half water | 10% | 1.06 lb | 8.00 lb | 21.2 lb | $0.23 |
| Whole wheat flour | 5% | 0.53 lb | 4.00 lb | 10.6 lb | $0.55 |
| Salt | 1.1% | 0.12 lb | 0.88 lb | 2.33 lb | $0.40 |
| The whole mix | 100% | 10.6 lb | 80 lb | 212 lb |
The 212 pounds cost $56.48 in ingredients, about 47 cents a loaf; the water is nearly two-fifths of the weight. Against the flour, the way bakers write it, that's about 74% water and 2% salt. The home-baking side is in north dakota cottage food laws.
The steps, at 212 pounds
- Build the levain. The night before, from a little starter, flour and water, sized to the run: 21 pounds for 212 pounds of dough.
- Mix by the mixer. Flour and water first, rested, then levain and salt; about 80 pounds a mix.
- Bulk ferment with folds. Three or four hours, folded every half hour at first.
- Divide by weight. About 1.75 pounds a loaf on a bench scale, pre-shaped, rested, shaped and into baskets.
- Proof overnight. Baskets covered in the cooler; the cold slows the rise and builds flavor.
- Bake from cold. Twelve loaves a deck, scored, with steam, until deeply browned.
- Cool and bag. Fully cooled before bagging, labeled with the day's lot and date.
The run takes about 14 hours of labor over two days, shaping one evening and baking the next morning.
What a loaf costs at each size
| Per loaf | Kitchen batch, 10.6 lb | Bulk run, 212 lb |
|---|---|---|
| Ingredients | $1.04 (grocery prices) | $0.47 (bought in bulk) |
| Packaging | $0.35 | $0.20 |
| Labor at $20 an hour | $5.00 (15 min a loaf) | $2.33 (7 min a loaf) |
| Cost of a loaf | $6.39 | $3.00 |
Flour by the 50-pound sack halves the ingredients, and the labor falls from 15 minutes a loaf to about 7, because a mixer and a deck oven take about the same work for 12 loaves as a bowl and a home oven take for 2. The labor is still most of a loaf's cost. Pricing is in how to price sourdough bread, and the margins in sourdough profit margin.
The overnight proof
A cold proof does two jobs in a bulk bakery: the shaping happens the evening before, and the oven runs the next morning on loaves that are all ready at once. It also makes a better loaf. The baskets take up cooler space, so a run is often limited by the cooler before the oven. The year's numbers are in sourdough business plan.
Get the calculator
Download the sourdough scaling calculator. Two sheets: scale the recipe, where you type each ingredient's percentage and cost a pound and the raw mix you want, and each ingredient's weight for the run fills in, with the mixes, oven loads, what comes out after the bake loss, the loafs it fills and the cost of each loaf; and weigh the loss, where what went in and came out over a few batches gives your average bake loss. It's an ordinary Excel file with no macros, and it works in Google Sheets, LibreOffice and Numbers.
Where this stops working
A country loaf, a seeded rye and a focaccia, bakes four days a week, flour from two mills, and a starter that's slow in winter. A sheet can say how much flour a run needs, but not whether there's enough for Friday, or whether the bake loss has crept up since the oven was serviced.
How TaroStack does it
TaroStack keeps the recipe by weight, takes each batch's ingredients off stock and checks its yield.
The recipe in the units you use. A recipe holds each ingredient by weight, with flour bought by the 50-pound sack and used by the pound, and the cost of every loaf comes from what you paid. "What could I make right now" says how many runs the flour and seeds on the shelf allow.
Each run a batch. A run takes its ingredients off stock, records the lots of flour it used, and gets a lot of its own for the loafs, with how much came out good, how much was rejected and the labor minutes.
Yield checked from history. From your own batch history, TaroStack says whether a recipe yields what it claims and which ingredient's quantity is off, so a bake loss that creeps up shows in the numbers. A sack of flour with weevils is an adjustment with its reason, spoiled, and shows in the waste report.
| The job | Spreadsheet | In TaroStack |
|---|---|---|
| Ingredients for Friday's run | Multiply, then check the shelf | What could I make right now |
| Which flour went into a run | Not written down | Lots recorded on the batch |
| The real bake loss | Weighed now and then | Good and rejected on every batch |
| Flour with weevils | Thrown out, forgotten | Adjustment with a reason |
Recipes, batches, lots and yield are on every plan, from $49 a month. The first 30 days are free, with no credit card. If you'd like a hand setting up, ask, and we'll do it with you.