How to use this calculator
Choose your mode at the top. “Feed my starter” is for routine maintenance feedings where you enter how much starter you have, pick a ratio, and get exact flour and water amounts. “Build starter for a recipe” helps you plan ahead when you need a specific amount of active starter by a certain time.
In feed mode, adjust the hydration percentage to see how flour and water amounts change at different hydration levels. The hydration adjustment table lets you compare 75%, 80%, 100%, and 125% hydration side by side so you can pick the consistency that works best for your baking style.
In recipe mode, enter the amount of starter your recipe calls for and how many hours you have. The calculator recommends a feeding ratio based on your timeline and creates a step by step schedule to build up enough starter.
Understanding starter ratios
The ratio describes how much fresh food (flour and water) you give your starter relative to the amount of existing starter you keep. A 1:1:1 ratio means equal parts starter, flour, and water. This is the quickest to peak, usually within 4 to 6 hours at room temperature.
Higher ratios like 1:5:5 give the starter much more food, which slows down fermentation and extends the time before the starter peaks. This is useful for overnight feeds, for building large quantities, or for managing your schedule when you cannot attend to the starter every few hours.
| Ratio | Peak Time (room temp) | Best For |
|---|---|---|
| 1:1:1 | 4 to 6 hours | Quick feeds, same day baking |
| 1:2:2 | 6 to 8 hours | Morning feed, evening bake |
| 1:3:3 | 8 to 10 hours | Overnight feeds |
| 1:5:5 | 10 to 14 hours | Long overnight, schedule flexibility |
Frequently asked questions
What do sourdough starter ratios like 1:1:1 and 1:5:5 mean?
The three numbers represent the weight proportions of existing starter, fresh flour, and fresh water. A 1:1:1 ratio uses equal parts of each. A 1:5:5 ratio uses 1 part starter to 5 parts flour and 5 parts water. Higher ratios provide more food for the yeast and bacteria, which extends the time before the starter peaks.
What does hydration percentage mean for sourdough starter?
Hydration is the weight of water divided by the weight of flour, expressed as a percentage. At 100% hydration, you use equal weights of flour and water, which produces a thick batter consistency. Lower hydration (75% or 80%) creates a stiffer starter that ferments more slowly. Higher hydration (125%) is thinner and pourable.
How often should I feed my sourdough starter?
At room temperature, feed every 12 hours or when the starter has peaked and begun to fall. In the refrigerator, once every 1 to 2 weeks is sufficient. Before baking, remove it from the fridge and give it 1 to 2 room temperature feeds to reactivate. Warmer kitchens may require more frequent feeding or a higher ratio.
How much starter do I need for a loaf of bread?
Most sourdough bread recipes call for about 100 grams of active starter per loaf. Two loaves typically need around 200 grams. Pizza dough usually requires about 150 grams. Always check your specific recipe and use this calculator to plan your feeding schedule so you have enough ready at bake time.