Every sourdough recipe is built on baker’s percentages — a system where every ingredient is expressed as a proportion of the total flour weight. That makes scaling up or down simple in theory, but the arithmetic is easy to get wrong when you factor in what the starter itself contributes. This calculator does the math for you. Select your banneton size or enter a target weight, set your hydration, inoculation, and salt percentages, and get exact ingredient weights in grams — ready to weigh out directly onto the scale.
Dough Weight Calculator
Target a specific loaf size and let Baker’s Math calculate the exact ingredient weights for you.
Common targets: 500g (mini), 900g (standard boule), 1800g (double batch).
What Is Baker’s Math — and Why It Matters
Baker’s math (also called baker’s percentages) is the standard system professional bakers use to express and scale recipes. Every ingredient is listed as a percentage of the total flour weight — not as a percentage of the total recipe weight. Flour is always 100%, and everything else is expressed relative to that.
For example, a recipe at 72% hydration means the water weighs 72% of whatever the flour weighs. If you have 500g of flour, you add 360g of water. If you scale up to 750g of flour, the water automatically becomes 540g. The ratio stays the same regardless of batch size.
This matters for home bakers because most published recipes are written for a specific loaf size that may not match your equipment. A recipe written for a 900g boule in an 8-inch banneton will overflow a 6-inch banneton or underfill a larger one. Rather than guessing or doing percentage conversions by hand, scaling from your target dough weight gives you precisely the right amount every time.
How Inoculation Affects the Math
Inoculation is the percentage of starter (by weight) relative to the total flour in the recipe. Most home recipes use 15–25%. What makes the math slightly tricky is that your starter is itself made of flour and water — usually in a 1:1 ratio. That means when you add 100g of starter to a dough, you are also adding approximately 50g of flour and 50g of water that many recipes do not account for separately.
The calculator handles this automatically. The “What Goes in the Bowl” section shows the net flour and water you actually measure out separately, after accounting for what the starter contributes. The “True Baker’s Totals” section shows the actual flour and water across the whole recipe including the starter — which is the correct way to verify your true hydration. For more on how hydration affects texture and handling, read our complete sourdough hydration guide.
Choosing the Right Hydration for Your Skill Level
Hydration is the ratio of water to flour, expressed as a percentage. It is the single biggest factor in how easy or difficult a dough is to handle, and it significantly affects the final crumb structure. As a general guide:
- 60–68% — Firm, easy-to-handle dough. Great for beginners and sandwich loaves. Tight, even crumb.
- 68–74% — Classic sourdough range. Slightly tacky, manageable. Good open crumb with proper technique.
- 74–78% — Sticky dough that rewards technique. Requires confident shaping and strong gluten development.
- 78%+ — Expert level. Wet, slack dough best suited to those comfortable with high-hydration handling. Very open, irregular crumb.
If you are new to sourdough, start at 70% and get comfortable with shaping before moving higher. Adding water is easy — developing the technique to handle it is the harder part.
How to Read Your Scaled Recipe
The calculator gives you two sets of numbers. Understanding the difference between them prevents the most common scaling mistakes.
What Goes in the Bowl
These are the amounts you physically weigh and add to your mixing bowl. The flour and water figures are net — meaning the flour and water already inside your starter have been subtracted, so you do not accidentally double up. Weigh out the flour first, then the water, then add the starter, then the salt last (salt inhibits starter activity if it contacts it directly before mixing).
True Baker’s Totals
These figures represent the entire recipe including what is inside the starter. The “True Hydration” percentage is the real hydration of your finished dough — not just the ratio of the separately added water to flour. For most home bakers at 20% inoculation, the difference is small (around 1–2%). At higher inoculations — 25–30% — the difference becomes more significant and can explain why a recipe behaves wetter than its stated hydration suggests.
Scaling Multiple Loaves
When baking more than one loaf, the calculator multiplies the total dough weight and shows per-loaf amounts separately. Weigh out the full batch together, then divide by weight when shaping — this is more accurate than trying to calculate per-loaf amounts and weigh each one separately. A kitchen scale and a dough scraper are all you need.
Frequently Asked Questions
What dough weight should I use for a standard sourdough loaf?
For an 8-inch round banneton (the most common size), 850–950g of dough is the right range. Under 800g and the loaf will not fill the banneton properly and may spread. Over 1,000g and it risks overflowing during proofing. For a 10-inch oval batard, 900–1,100g works well. For a 9×5-inch loaf pan, 800–900g is the typical range.
Why does this calculator show different flour and water amounts than my recipe?
Most published recipes list total flour (including the flour inside the starter) as the base, then list the starter as a separate addition. This calculator separates the two clearly: the net amounts show what you add to the bowl on top of the starter, and the true totals show the full picture. If your recipe says “500g flour + 100g starter + 350g water,” you can verify the true hydration by dividing total water (350g + 50g from starter) by total flour (500g + 50g from starter) = 400 ÷ 550 = 72.7%.
What does inoculation percentage mean in sourdough?
Inoculation is the weight of starter expressed as a percentage of the total flour weight. A 20% inoculation means 20g of starter for every 100g of flour — or 100g of starter for a recipe with 500g of flour. Higher inoculation speeds up fermentation (more active organisms working from the start); lower inoculation slows it down. Most home recipes use 15–25%, with higher percentages useful in cold kitchens and lower percentages useful in warm ones.
Does changing hydration affect the dough weight?
Yes — for a fixed total dough weight target, increasing hydration means less flour and more water (since the total is the same but the ratio shifts). The flour weight decreases slightly and the water weight increases. For a fixed flour weight, total dough weight increases as hydration increases. The calculator works from the total dough weight target, so it automatically adjusts all ingredients when you change hydration.
Can I use this calculator for enriched doughs with butter, eggs, or oil?
This calculator is designed for lean sourdough doughs — flour, water, starter, and salt only. Enriched doughs (those with butter, eggs, oil, or dairy) do not follow the same baker’s percentage structure, because fats and eggs affect hydration in complex ways and contribute to dough weight without functioning like water. For enriched sourdough recipes, the percentages in this calculator will not give accurate results.