Every good loaf starts before you touch the dough. This calculator works backwards from what you want — how many loaves, how heavy — and gives you the exact gram weights for flour, water, starter, and salt. No estimating. No mental arithmetic. Just numbers you can trust before you start.
Whether you are baking a single test loaf on a Sunday afternoon or scaling up for a weekend batch of eight, the math is the same. Baker's percentages keep every ingredient in proportion to your flour weight, so the recipe behaves the same whether you are baking 500 g of dough or 5 kg.
A 5% swing in hydration is the difference between a tight, sliceable loaf and a slack dough that spreads on the counter. When you measure by eye or volume, that 5% gap is easy to miss. When you measure by gram weight from a calculated recipe, it disappears. The crumb you want is a math problem first, then a shaping problem.
Sourdough flour, especially stone-milled or heritage varieties, is not cheap. Knowing your ingredient weights upfront means you buy what you need and nothing more. Scaled correctly, a 1 kg bag of flour yields predictable, repeatable results — not a different loaf every weekend based on how the bag looked when you scooped.
Too much salt slows fermentation and overpowers flavour. Too little and the dough is flat and bland. Starter percentage directly affects how long your bulk fermentation runs — too high and it's over before you're ready; too low and you're waiting hours longer than planned. These are not ingredients to eyeball.
Most home bakers work with a Dutch oven that fits one loaf, or a proofing basket rated to 800 g. Knowing your dough weight per loaf before you mix means your equipment fits your batch — not the other way around. Scale down to fit a smaller oven. Scale up to fill a larger one. The calculator adjusts everything proportionally.
Most calculators start with a flour weight and ask you to calculate everything else. This one works the other direction: you tell it what you want to end up with, and it figures out the flour.
Enter the number of loaves you want to bake and the target weight per loaf in grams. A standard country loaf is typically 800–900 g. A batard is closer to 700 g. A large miche can run 1,200 g or more.
Enter hydration, salt, and starter as baker's percentages — each expressed relative to flour weight. The defaults (75% hydration, 2% salt, 20% starter) are a reliable starting point for most home bakers.
The calculator solves for your flour weight first, then derives water, starter, and salt from it. Every number is in grams — ready to read off a digital scale. No cups, no tablespoons, no conversion guesswork.
Use this table as a starting point for different loaf styles. All weights are calculated for a single 850 g target loaf using 100% hydration starter.
| Loaf Style | Hydration | Flour (g) | Water (g) | Starter (g) | Salt (g) | Total (g) | Character |
|---|---|---|---|---|---|---|---|
| Beginner Loaf | 65% | 519 | 337 | 104 | 10.4 | 850 | Firm, easy to shape. Tight crumb. Good for first loaves. |
| Country Loaf | 75% | 480 | 360 | 96 | 9.6 | 850 | Balanced handling with a semi-open crumb. The everyday loaf. |
| Open Crumb | 80% | 461 | 369 | 92 | 9.2 | 850 | Airy crumb with irregular holes. Needs strong gluten development. |
| High Hydration | 85% | 444 | 377 | 89 | 8.9 | 850 | Very slack dough. Experienced bakers only. Exceptional crust. |
| Rye Blend (20% Rye) | 75% | 480 | 360 | 96 | 9.6 | 850 | 96 g of flour is rye. Earthy flavour, faster fermentation. |
| Weekend Batch (×6) | 75% | 2,880 | 2,160 | 576 | 57.6 | 5,100 | Six loaves at 850 g. Same percentages, scaled proportionally. |
All values rounded to the nearest gram. Starter at 20% of flour weight. Salt at 2% of flour weight. Calculated dough weight — baked loaves will be 10–15% lighter.
A cup of flour can vary by 20–30 g depending on how it is scooped. A digital kitchen scale accurate to 1 g is the single most impactful tool investment a home baker can make — and they cost less than a bag of good flour.
Your ingredient ratios stay fixed, but fermentation speed is dictated by temperature. A kitchen at 18°C will run a bulk fermentation twice as long as one at 26°C. Use these weights as your constant; treat time as your variable.
Write down every batch — weights, times, temperature, result. Consistent measurements mean your notes are actually useful. When a loaf comes out perfectly, you can reproduce it. When it doesn't, you know exactly what to adjust.
Your inputs are saved in the page URL automatically. Copy it to bookmark a recipe, share it with another baker, or pick up exactly where you left off. No account needed.
Common questions about scaling sourdough recipes, baker's percentages, and getting consistent results from your dough.
Good bread is repeatable bread. The bakers who consistently produce loaves with an open crumb, a cracking crust, and a flavour worth talking about are not necessarily more talented — they are more precise. They know exactly what went into the dough, every single time.
This calculator removes the one part of sourdough baking that trips most people up: the math between what you want to bake and what you need to mix. Set your target, get your weights, then focus your attention on the dough — the feel of it under your hands during folding, the smell of it at the end of bulk fermentation, the sound of it when it hits a hot Dutch oven.
The numbers are a starting point. Every flour behaves slightly differently, every kitchen has its own temperature rhythm, and every starter has its own personality. Use this calculator to get your baseline right, then adjust from there — and write it all down when you do.
Found an issue or want a new calculator? We'd love to hear from you.