Sourdough fails when bakers follow timers instead of their dough. Temperature, starter health, hydration, and flour type all change how your dough behaves — and no recipe can account for all of them. These calculators do. Each one takes your actual conditions and gives you precise numbers, so you stop guessing and start baking predictably.
Sourdough Calculators
These free sourdough calculators take the guesswork out of hydration, fermentation timing, starter feeding, and recipe scaling. No more failed bakes from following a timer blindly.
Sourdough Hydration Calculator
Calculate your precise sourdough hydration percentage and total dough weight based on flour, water, and starter inputs.
Sourdough Starter Feeding Calculator
Determine the exact ratios of flour and water needed to refresh your starter for your next bake.
Dough Weight Calculator
Scale your favorite recipes up or down to perfectly fit any banneton size or loaf pan.
Bake Planner
Map out your entire sourdough timeline, from the initial feeding to the final cooling rack.
Fermentation Matrix
Predict your bulk fermentation window based on kitchen temperature and starter activity.
Why Sourdough Calculators Make a Real Difference
Most sourdough recipes are written for one kitchen, one starter, and one flour. Yours is different. A recipe that says “bulk ferment for 5 hours” was written at a specific temperature — probably not yours. A hydration percentage that works for one baker’s bread flour will behave completely differently with all-purpose or whole wheat.
That’s why so many bakers follow recipes perfectly and still get dense, gummy, or flat loaves. The recipe isn’t wrong — the variables are just different in your kitchen.
These calculators account for your specific inputs. Whether you’re trying to understand sourdough hydration, figure out the right amount of starter to use, or plan your bake schedule around a busy day, you’ll get numbers that actually apply to your bake — not someone else’s.
Frequently Asked Questions
What is baker’s percentage in sourdough?
Baker’s percentage expresses every ingredient as a percentage of the total flour weight. Flour is always 100%. If you use 350g of water with 500g of flour, your hydration is 70%. This system makes it easy to scale recipes up or down and compare different recipes accurately, regardless of batch size.
How do I calculate sourdough hydration?
Divide the total water weight by the total flour weight, then multiply by 100. For example: 375g water ÷ 500g flour × 100 = 75% hydration. Remember to include the water and flour inside your starter in this calculation for precise results — our Hydration Calculator handles this automatically.
How much starter should I use per loaf?
A standard starting point is 20% inoculation — meaning your starter weight equals 20% of your total flour weight. For a 500g flour loaf, that’s 100g of starter. In a warm kitchen (above 77°F), reduce this to 15% to slow fermentation. In a cool kitchen (below 65°F), you can increase to 25% to compensate for the slower activity.
How long should I bulk ferment sourdough?
Bulk fermentation time depends almost entirely on your kitchen temperature and starter strength — not a fixed number of hours. At 72°F with an active starter, expect 5–7 hours. At 65°F, expect 10–13 hours. At 80°F, it could be done in 2.5–3.5 hours. Use our Bake Planner to get a precise window based on your actual conditions.
Can I use these calculators for whole wheat or rye sourdough?
Yes — the Bake Planner and Hydration Calculator both account for flour type. Whole wheat and rye absorb more water and ferment faster than white flour because the bran particles accelerate yeast activity. If you’re switching from white to whole grain flour, expect a shorter bulk fermentation window and slightly stickier dough that firms up after the first set of stretch and folds.
Learn the Fundamentals
The calculators give you the numbers — these guides explain the reasoning behind them.