What this tool does
The Sourdough Calculator converts baker's percentages into exact gram weights for every ingredient in your sourdough recipe. Enter your total flour weight, desired dough hydration, and starter percentage, and the calculator instantly gives you precise measurements for flour, water, starter, and salt.
Baker's math is designed so every ingredient is expressed as a percentage of the total flour weight. This makes it trivial to scale any recipe up or down without recalculating each ingredient manually.
Understanding baker's percentages
Baker's percentages use flour as the base (100%). All other ingredients are expressed relative to flour:
- **Hydration (75%)**: For 500g flour, you need 375g of total water - **Starter (20%)**: For 500g flour, you need 100g of starter - **Salt (2%)**: For 500g flour, you need 10g of salt
The water in your starter contributes to total hydration, so this calculator accounts for that automatically (assuming 100% hydration starter — equal parts flour and water by weight).
Hydration levels explained
Hydration affects the texture, crust, and crumb of your bread:
- **65–70%**: Lower hydration, easier to handle, denser crumb — good for beginners - **72–78%**: Medium hydration, balanced workability and open crumb — most popular range - **80–85%**: High hydration, sticky and challenging to shape, very open crumb - **85%+**: Extreme hydration, used by experienced bakers for ciabatta-style loaves
If you're new to sourdough, start at 72–75% hydration and work up as you develop feel for the dough.
Starter percentage guidance
The amount of starter (also called levain or inoculation rate) affects fermentation speed and flavor:
- **10–15%**: Slower rise, more sour, better for overnight cold fermentation - **20–25%**: Standard range, flexible timing, balanced flavor - **30–50%**: Faster rise, milder flavor, good for warmer kitchens or quick bakes
Most home bakers use 15–25% starter. Hotter kitchen temperatures call for less starter to avoid over-proofing.
How to use
1. Enter your target flour weight in grams (try 500g for a standard loaf) 2. Set your desired hydration using the slider or input field 3. Set your starter percentage — 20% is a good default 4. Adjust salt percentage if needed (1.8–2.2% is standard) 5. Click Calculate Ingredients to see all measurements 6. Measure each ingredient on a kitchen scale for best results
FAQs
Q: Why does the calculator show "added water" instead of total water? A: Your starter already contains water (assuming 100% hydration starter, it's half flour, half water). The calculator subtracts the water already in your starter so you don't add too much.
Q: What if my starter isn't 100% hydration? A: Most home bakers maintain 100% hydration starter (equal parts flour and water by weight). If yours is stiffer or wetter, the total water will be slightly off — adjust by a few grams until the dough feels right.
Q: Can I use this for whole wheat or rye flour? A: Yes. Enter the total flour weight regardless of flour type. Keep in mind whole grain flours absorb more water, so you may want to reduce hydration by 5–10% for your first attempt.
Q: How do I scale this recipe? A: Just change the flour weight. Everything scales proportionally — that's the power of baker's percentages.
Q: What's a good starter-to-flour ratio for overnight cold fermentation? A: Use 10–15% starter, mix in the evening, and cold ferment in the fridge for 12–16 hours. This develops more complex sour flavor.