Sourdough Calculator
Enter your flour weight and desired hydration to get exact ingredient weights for your sourdough loaf in grams or ounces. Adjust starter percentage and salt, choose a bread-type preset, and the calculator works out every component using baker's math, including how much flour and water live inside your starter. Results update as you type.
What is baker's percentage and why use it?
Baker's percentage (also called baker's math) expresses every ingredient as a proportion of the total flour weight, which is always 100%. So a recipe with 72% water means 72 g of water for every 100 g of flour, regardless of batch size. This system makes scaling trivial: double the flour, double every other ingredient by the same amount. It also makes recipes instantly comparable. You can tell at a glance that a 62% pizza dough is much stiffer than a 80% ciabatta, even if the raw weights look similar. Professional bakeries worldwide use baker's math for exactly this reason.
How starter affects your flour and water totals
Sourdough starter is itself a mixture of flour and water, so it contributes to both totals. A 100% hydration starter (equal parts flour and water by weight) adds equal grams of each. If you use 90 g of starter at 100% hydration, that is 45 g of flour and 45 g of water going into the dough. This calculator accounts for that automatically: it computes how much flour and water live inside your starter, adds them to the base flour and water, and then works backwards to find how much extra water you need to reach your target hydration. Ignoring the starter's contribution is a common beginner mistake that results in wetter dough than intended.
Choosing your hydration and starter percentage
Hydration determines how open and chewy your crumb will be, and how difficult the dough is to shape. Beginners are usually advised to start at 68-72%, which produces a workable dough with a good crumb. Above 78% the dough gets very slack and requires advanced techniques such as coil folds, lamination and a well-floured linen couche. Starter percentage controls fermentation speed: 20% starter at 75 F (24 C) typically needs 8-12 hours of bulk fermentation, while 5% might need 18-24 hours and develop more complex sour notes. Temperature matters too - every 10 F (6 C) drop roughly doubles fermentation time.
How to use this calculator
Choose a bread type preset to fill in typical values, or select Custom to enter your own. Enter your flour weight (the weight of actual flour, not the total dough weight). Set your target hydration percentage, starter percentage, starter hydration, and salt percentage. The calculator immediately shows you the gram weights for every ingredient, the true hydration after accounting for the starter's composition, and a dough weight chart across the hydration range. The steps panel shows every calculation so you can verify the math. If you want to scale up or down, just change the flour weight - all other weights adjust proportionally.
Hydration ranges by bread type
| Bread type | Hydration | Starter % | Handling difficulty |
|---|---|---|---|
| Bagel | 55-60% | 10-15% | Easy |
| Sandwich bread | 62-66% | 15-20% | Easy |
| Baguette | 65-70% | 10-15% | Moderate |
| Classic sourdough | 70-75% | 15-25% | Moderate |
| Ciabatta | 75-82% | 15-20% | Advanced |
| Focaccia | 78-85% | 15-20% | Easy (pan) |
Baker's percentage hydration for common bread styles. Higher hydration = more open crumb, more advanced shaping.
Frequently asked questions
What hydration should a beginner sourdough baker use?
65-72% is a great starting range. At these hydration levels the dough is firm enough to hold its shape during shaping and scoring, but still produces a pleasingly open crumb. Once you are comfortable with stretch-and-fold techniques and can read dough strength by feel, you can push toward 75-80% for a more open, glossy crumb.
What does starter percentage actually control?
Starter percentage (inoculation rate) primarily controls how quickly your dough ferments. A 20% starter at 75 F (24 C) typically needs 8-12 hours of bulk fermentation. Doubling it to 40% can halve that time. Lower starter percentages (5-10%) produce slower, cooler ferments that often develop more acidity and complexity. Temperature amplifies the effect: a warm kitchen will ferment much faster than a cool one at any given starter percentage.
How do I know if my starter hydration is 100%?
A 100% hydration starter is fed with equal weights of flour and water. If you feed it 50 g flour and 50 g water, it is 100% hydration. Some bakers prefer a stiff 50-65% starter, which ferments more slowly and often tastes less sour. Others use a liquid 125% starter. Just enter your actual starter hydration here and the calculator adjusts the added water accordingly.
Why is my true hydration different from my target hydration?
The target hydration you enter is used to calculate how much total water you need relative to total flour (including starter flour). Because the starter contributes both flour and water, the true hydration - total water divided by total flour - should equal your target hydration exactly. If you see a small difference, it is a rounding artifact. The calculator shows the true hydration as a check.
How much salt should I use in sourdough?
Most sourdough bakers use 1.8-2.2% salt by flour weight. At 2% on 450 g of flour you add 9 g of salt. Salt does more than flavor: it tightens the gluten network, slows fermentation slightly, and contributes to crust color. Going below 1.5% makes the dough feel slack and fermentation accelerates; going above 2.5% can inhibit the yeast and lactic bacteria in your starter.
Can I use this calculator for commercial yeast bread?
The flour, water, and salt calculations work the same way for any bread dough. The starter field is specific to sourdough: for commercial yeast, simply set starter to 0% (or a very low value) and add your yeast outside the calculator. Baker's percentages are universal - the same math applies to baguettes, pizza, and enriched doughs.