Baker's percentage (also called baker's math or flour-weight percentage) is a notation system where every ingredient in a bread recipe is expressed as a percentage of the total flour weight. Flour is always 100%. Every other ingredient is stated as a proportion relative to that flour.
If a recipe uses 500 g of flour and 350 g of water, the water is 70% (because 350 / 500 = 0.70). If it uses 10 g of salt, the salt is 2% (because 10 / 500 = 0.02). The flour itself is 100%, always, by definition.
This system has been used by professional bakers for centuries. It is not a peculiarity or a shortcut; it is the standard language of bread baking worldwide. Once you understand it, you can read any professional recipe at a glance, scale recipes to any size instantly, and compare recipes meaningfully even when they are written for different quantities.
Fixed-weight recipes are fragile. A recipe that says "500 g flour, 350 g water, 10 g salt, 100 g starter" works for exactly one loaf size. If you want to make two loaves, you double everything. If you want to use 600 g of flour instead, you need to recalculate every ingredient. And if you want to compare this recipe to another one that uses 800 g of flour, the raw numbers tell you nothing about the character of the dough.
Baker's percentage solves all three problems at once:
The conversion process is simple. Take the weight of each ingredient and divide it by the total flour weight, then multiply by 100.
Formula: Ingredient % = (Ingredient weight / Total flour weight) x 100
Let us convert a typical sourdough recipe to baker's percentage.
Original recipe (fixed weights):
Step 1: Find total flour. Add all the flour in the recipe: 450 + 50 = 500 g. This is your 100% baseline.
Step 2: Divide each ingredient by total flour.
The recipe in baker's percentage:
| Ingredient | Baker's % |
|---|---|
| Bread flour | 90% |
| Whole wheat flour | 10% |
| Water | 70% |
| Sourdough starter (100% hydration) | 20% |
| Salt | 2% |
Notice that bread flour and whole wheat flour together add up to 100% (90% + 10% = 100%). Total flour is always 100%. If you use three types of flour, their percentages must add up to 100%.
Going from percentages to grams is equally straightforward. Choose how much flour you want to use, then multiply each percentage by that flour weight.
Formula: Ingredient weight = (Ingredient % / 100) x Total flour weight
Using the same recipe percentages from above, let us scale up to 800 g of total flour (for two larger loaves):
| Ingredient | Baker's % | Weight (g) |
|---|---|---|
| Bread flour | 90% | 800 x 0.90 = 720 g |
| Whole wheat flour | 10% | 800 x 0.10 = 80 g |
| Water | 70% | 800 x 0.70 = 560 g |
| Starter | 20% | 800 x 0.20 = 160 g |
| Salt | 2% | 800 x 0.02 = 16 g |
The ratios are identical; only the total quantity changed. The dough will behave the same way, just in a larger batch. The sourdough calculator automates this process: enter your target flour weight and the percentages, and it gives you exact gram amounts for every ingredient.
This is the part that trips up most home bakers. Your sourdough starter is not a single ingredient; it is a mixture of flour and water. When you add 100 g of a 100% hydration starter, you are actually adding 50 g of flour and 50 g of water to the dough.
There are two ways baker's percentage handles this, and both are correct. Understanding the difference is essential for precise baking.
In this approach, you list the starter as its own line item and the flour and water listed in the recipe are only the amounts you add directly. This is the most common method in home baking recipes and is what the table above shows. The percentages are relative to the flour you measure out yourself.
This method is simple and practical. The drawback is that the listed "hydration" (70% in our example) is not the true hydration of the final dough, because it does not account for the water inside the starter.
In this approach, you decompose the starter into its flour and water components and add those to the totals. The total flour becomes the recipe flour plus the flour in the starter, and the total water becomes the recipe water plus the water in the starter.
Using our example recipe with 100 g of 100% hydration starter:
This is a more accurate picture of what the dough actually contains. The hydration guide explains this concept in more detail, and the starter hydration article walks through the math for different starter types.
When you see a sourdough recipe in baker's percentage, certain numbers immediately tell you about the character of the bread. Here is what to look for.
| Hydration % | What It Means |
|---|---|
| 55-65% | Low hydration. Stiff, easy-to-shape dough. Tight crumb. Good for bagels, rolls, enriched breads. |
| 65-72% | Medium hydration. Manageable dough. Even crumb with moderate openness. The comfort zone for most home bakers. |
| 72-80% | High hydration. Sticky, extensible dough. Open crumb. Requires good technique. Classic artisan sourdough territory. |
| 80%+ | Very high hydration. Wet, slack dough. Very open crumb. Ciabatta, focaccia, and advanced artisan loaves. |
| Salt % | What It Means |
|---|---|
| 1.5% | Low salt. Bland to most palates. Sometimes used in Tuscan-style bread (pane sciocco), which is traditionally unsalted or lightly salted. |
| 1.8-2.0% | Standard range. Well-balanced flavor. Most recipes fall here. This is the sweet spot where salt enhances flavor without dominating it. |
| 2.2-2.5% | Higher salt. Richer flavor, slightly slower fermentation. Some bakers prefer this for breads with long cold retards. |
Salt also controls fermentation speed. Higher salt percentages slow down yeast and bacterial activity. If you reduce salt, expect faster fermentation and a sourer flavor profile. If you increase it, expect slower fermentation and a milder tang.
| Starter % | What It Means |
|---|---|
| 5-10% | Low inoculation. Very slow fermentation (12-24+ hours). Mild, complex flavor. Common in long cold-retard recipes and professional bakery formulas. |
| 15-20% | Standard range. Moderate fermentation time (4-8 hours at room temperature). Good balance of flavor and convenience. Most home recipes use this range. |
| 25-35% | High inoculation. Faster fermentation (3-5 hours). More pronounced sour flavor. Useful in cold climates or when you want a quicker bake. |
The table below shows the full range of baker's percentages you will encounter in sourdough recipes. Use it as a reference when reading recipes, designing your own formula, or checking whether a recipe looks reasonable.
| Ingredient | Typical Range | Common Default | Notes |
|---|---|---|---|
| Total flour | 100% | 100% | Always 100% by definition |
| Water | 60-90% | 70-75% | See the hydration guide for details |
| Salt | 1.5-2.5% | 2% | Fine sea salt or kosher salt by weight |
| Starter | 5-35% | 20% | Percentage of starter (not just the flour in it) |
| Olive oil | 0-10% | 3-5% (if used) | Common in focaccia and enriched breads |
| Sugar / honey | 0-10% | 2-5% (if used) | Adds flavor, browning, and softness |
| Butter | 0-20% | 5-10% (if used) | Enriched breads like brioche |
| Seeds / add-ins | 0-30% | 10-15% (if used) | Seeds, nuts, dried fruit, olives, etc. |
Let us walk through a full sourdough recipe from percentages to final weights, step by step.
Target recipe: A country-style sourdough boule with 15% whole wheat, 75% hydration, 2% salt, and 20% starter (100% hydration). Target total flour: 500 g.
The 100 g of 100% hydration starter contains 50 g flour and 50 g water. So the effective totals are:
The listed hydration is 75%, but the effective hydration is 77.3% because the starter contributes extra water relative to the extra flour it brings. This is a subtle but important distinction, especially at higher starter percentages.
| Ingredient | Baker's % | Weight |
|---|---|---|
| Bread flour | 85% | 425 g |
| Whole wheat flour | 15% | 75 g |
| Water | 75% | 375 g |
| Sourdough starter (100% hydration) | 20% | 100 g |
| Salt | 2% | 10 g |
| Total dough weight | 985 g |
This gives you a dough weight of about 985 g, which is perfect for a single large boule or two smaller loaves.
One of the biggest advantages of baker's percentage is effortless scaling. Here are some common scenarios.
You bought a 1 kg bag of flour and want to use 750 g for bread. Simply multiply each percentage by 750 g (or 7.5 for each percentage point):
You want exactly 900 g of dough (for a standard loaf pan). First, add up all the percentages:
Then divide the target dough weight by the total percentage:
This reverse-calculation is especially useful for pan breads where you need a specific dough weight to fill the pan properly. The sourdough calculator can do this calculation for you in either direction.
If you have a recipe in percentages, halving or doubling is trivial: just halve or double the flour weight. All the percentages stay the same. A 500 g flour recipe at 72% hydration becomes a 250 g flour recipe at 72% hydration. Nothing else changes.
In baker's percentage, the numbers do not add up to 100%. A recipe might have 100% flour, 72% water, 20% starter, and 2% salt, totaling 194%. This is normal. Baker's percentage is not about proportions of the whole; it is about each ingredient's relationship to flour.
When calculating the true hydration of a dough, you must account for the flour and water inside the starter. A recipe listed at 70% hydration with 20% starter (100% hydration) actually has an effective hydration closer to 73%. This matters when you are trying to hit a specific dough consistency. Read the starter hydration guide for a thorough explanation.
The denominator is always total flour, never total dough. Dividing water by total dough weight gives you a much smaller number that is not baker's percentage.
If your recipe uses bread flour, whole wheat flour, and rye flour, you must add all three together to get the total flour (100%). A common mistake is to only count the "main" flour and treat the others as add-ins. All flours contribute to the 100% base.
Baker's percentage only works with weight measurements. "1 cup of flour" is not a meaningful base for percentages because the weight of a cup varies wildly. Always use a kitchen scale.
Baker's percentages are descriptive, not prescriptive. A "70% hydration" recipe is a starting point. Your flour, your climate, and your technique may require you to adjust by a few percentage points. The numbers help you communicate and scale, but your hands and eyes make the final call.
Professional bakeries rely on baker's percentage to manage production. A head baker might define a formula once (say, 100% bread flour, 72% water, 2% salt, 15% levain), and then every morning, an assistant baker calculates the exact gram amounts based on how many loaves they need that day. Without baker's percentage, this daily scaling would be tedious and error-prone.
Published bread books almost universally use baker's percentage alongside gram weights. When you read a book like Chad Robertson's Tartine Bread, Jeffrey Hamelman's Bread, or Ken Forkish's Flour Water Salt Yeast, the percentages are always there in the formula tables. Learning to read them will make every bread book more accessible.
Baker's percentage is the simplest, most powerful tool for understanding bread recipes. Flour is always 100%. Everything else is relative to flour. You can convert any recipe to percentages by dividing each ingredient by the total flour weight, and convert back by multiplying each percentage by your desired flour weight.
The key numbers to pay attention to are hydration (which determines dough feel and crumb openness), salt (which controls flavor and fermentation speed), and starter percentage (which determines fermentation time and sourness). Remember that your starter's hydration affects the true flour and water balance of your dough.
Use the sourdough calculator to skip the math and get exact ingredient weights for any formula.
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