Baker’s percentage is a numbering system where every ingredient in a bread recipe is expressed as a percentage of the total flour weight, and flour itself is always 100%. If a recipe uses 500 g of flour and 330 g of water, the water percentage is (330 ÷ 500) × 100 = 66%. That single number tells you the dough hydration immediately, no matter the batch size.
King Arthur Baking’s professional reference describes baker’s percentage as the shared language that lets bakers “quickly assess a formula simply by seeing the percentages.”
Why Every Bread Baker Should Know This
Volume measures break down when you scale. A recipe that calls for “3 cups of flour” gives you no way to know what proportion of water or salt is in the dough. Baker’s percentage fixes that:
- Scale up or down by changing one number (total flour weight)
- Spot mistakes instantly — 10% salt is obviously wrong; 2% is normal
- Compare any two bread recipes on the same terms
- Reproduce results batch after batch with a scale
The Core Formula
Ingredient % = (ingredient weight ÷ flour weight) × 100
To go the other way — from percentage to weight:
Ingredient weight = (percentage ÷ 100) × flour weight
Worked Example: White Sandwich Loaf
Start with 500 g of bread flour and calculate everything else:
| Ingredient | Weight | Calculation | Baker’s % |
|---|---|---|---|
| Bread flour | 500 g | baseline | 100% |
| Water | 330 g | (330 ÷ 500) × 100 | 66% |
| Salt | 10 g | (10 ÷ 500) × 100 | 2% |
| Instant yeast | 4 g | (4 ÷ 500) × 100 | 0.8% |
| Total dough | 844 g | 168.8% |
Now suppose you want 1,200 g of dough instead. Divide desired dough weight by total percentage: 1,200 ÷ 168.8 = 7.11. Multiply each percentage by 7.11:
| Ingredient | Weight |
|---|---|
| Bread flour | 7.11 × 100 = 711 g |
| Water | 7.11 × 66 = 469 g |
| Salt | 7.11 × 2 = 14 g |
| Instant yeast | 7.11 × 0.8 = 5.7 g |
That is called the Formula Conversion Factor method, and it works at any scale — from a single dinner roll to a commercial batch.
Reference Percentages for Common Breads
These ranges come from King Arthur Baking and professional bread literature:
| Bread type | Hydration | Salt | Yeast (instant) |
|---|---|---|---|
| Baguette | 65–68% | 2% | 0.3–0.5% |
| Sandwich loaf | 62–68% | 2% | 1–1.5% |
| Country sourdough | 70–78% | 2% | — (starter) |
| Ciabatta | 75–82% | 1.8% | 0.3–0.5% |
| Focaccia | 75–80% | 2% | 0.5–1% |
| Bagel | 55–60% | 1.8–2% | 1–1.5% |
| Brioche | 45–55% (+ eggs/butter) | 2% | 1–1.5% |
Salt should stay in the 1.8–2.2% range. Below 1.5% the bread tastes flat; above 2.5% yeast activity slows noticeably. For more on salt’s role, see the salt percentage in bread guide.
Baker’s Percentage vs. Batch Percentage
Baker’s percentage and batch percentage are not the same:
- Baker’s percentage: each ingredient divided by flour weight. Flour = 100%. Total always exceeds 100%.
- Batch percentage: each ingredient divided by total batch weight. All ingredients together = 100%.
Baker’s percentage is the standard for breads, where flour dominates the formula. Batch percentage is used for cakes, cookies, and pastries where sugar and fat play larger roles. King Arthur’s baker’s math guide explicitly recommends switching to batch percentages for cakes, scones, and biscuits.
Example of a pound cake in batch percentage: equal parts flour, butter, eggs, and sugar by weight — each is 25% of the total batch weight.
Enriched Dough Example: Brioche
Enriched doughs include fat, eggs, and sugar alongside the standard flour/water/salt/yeast. Baker’s percentage handles them the same way — everything is still divided by flour weight:
| Ingredient | Weight | Baker’s % |
|---|---|---|
| All-purpose flour | 500 g | 100% |
| Water | 45 g | 9% |
| Salt | 10 g | 2% |
| Instant yeast | 15 g | 3% |
| Eggs | 250 g | 50% |
| Butter | 250 g | 50% |
| Sugar | 50 g | 10% |
| Total | 1,120 g | 224% |
The low water percentage looks odd, but eggs and butter each contain significant water (eggs ~75%, butter ~16%) — the “effective hydration” when you include ingredient moisture is closer to 55%. This is why brioche feels much wetter than a 9% water figure suggests.
Handling Multiple Flours
When a recipe blends two or more flours — say, 400 g bread flour and 100 g whole wheat — the total flour weight is 500 g. Individual flours are then percentages of that total: bread flour = 80%, whole wheat = 20%. Everything else is still divided by 500 g.
Baker’s Percentage With a Sourdough Starter
A 100%-hydration starter contains equal weights of flour and water. If your recipe calls for 200 g of ripe starter, that represents 100 g of flour and 100 g of water. Include both in your total flour and water counts when computing the overall formula percentage.
Many bakers also express how much flour is pre-fermented: pre-fermented flour % = starter flour ÷ total flour. Common ranges are 10–25%. Higher percentages speed fermentation and add tang. Using a biga (stiff preferment at 60% hydration) or poolish (liquid preferment at 100% hydration) follows the same logic — break each into its flour and water components and include both in the running totals.
Use the baker’s percentage calculator to run the math automatically for any flour weight or desired dough size.
Common Mistakes
- Using volume instead of weight. Percentages only work with weights. A cup of flour weighs 120–150 g depending on how it’s scooped, which throws off every ratio.
- Forgetting flour in the starter. If your recipe uses a preferment, add the flour and water it contains to your running totals.
- Rounding aggressively early. Round at the end, after calculating weights. Rounding each ingredient independently compounds errors.
- Confusing baker’s % with batch %. A 50% butter in baker’s percentage means 250 g of butter per 500 g flour — a rich brioche. In batch percentage, 50% butter would mean butter is half the recipe by weight, which is a different formula entirely.
Once you can read a formula in baker’s percentages, you can predict how a dough will behave before you mix it. See dough hydration guide for the practical effects of different water percentages.