This calculator helps home bakers determine the exact flour and water amounts needed to maintain their sourdough starter at a specific hydration ratio. Simply input your current starter weight, desired hydration level, and target total weight to get a precise feeding recipe. It takes the guesswork out of daily kitchen routines so your dough rises consistently every time.
Sourdough Starter Feeding Calculator
How to Use This Tool
- Enter the total weight of your active sourdough starter currently sitting in the jar.
- Specify how much starter you want to keep for the next feeding cycle (typically 20–50 grams).
- Input your target hydration percentage. Standard recipes use 100%, while stiffer starters use 60–80%.
- Set the target total weight for your refreshed starter, which should cover your upcoming baking needs.
- Choose your preferred unit (grams or ounces) and click Calculate to see your exact feeding measurements.
Formula and Logic
The calculator uses a straightforward hydration ratio to split your target weight into flour and water components. First, it subtracts the amount you plan to keep from the target total weight to find the remaining mass for new ingredients. It then divides this remainder based on your chosen hydration percentage using the formula: Flour = Remaining / (1 + Hydration/100). Water is simply the remainder minus the calculated flour. Finally, it determines your discard by subtracting the kept amount from your current starter weight.
Practical Notes
- Always weigh ingredients in grams for the highest accuracy, as volume measurements vary significantly with flour density.
- If you bake frequently, keep a higher baseline weight to avoid excessive discarding. For occasional baking, a 1:5:5 ratio (starter:flour:water) works well.
- Whole grain flours absorb more water than all-purpose or bread flour. You may need to adjust hydration by 5–10% when switching flour types.
- Store your maintained starter in the refrigerator and feed it only once a week to save time and reduce waste.
Why This Tool Is Useful
Maintaining a sourdough culture requires consistent ratios to keep the yeast and bacteria balanced. Guessing measurements often leads to overly runny or stiff starters, which directly impacts dough rise and crumb structure. This tool eliminates trial-and-error feeding, scales your recipe to match your exact baking schedule, and helps you track discard so you can repurpose it for pancakes, crackers, or waffles instead of throwing it away.
Frequently Asked Questions
Can I use volume measurements instead of weight?
While the calculator supports ounces, weight is strongly recommended for sourdough. Flour compacts differently in cups, which can throw off hydration ratios and weaken your starter over time. A basic kitchen scale ensures repeatable results every time.
What should I do with the discard?
Discard is simply unfed starter and remains highly useful. You can store it in a separate container in the fridge for up to two weeks and use it in recipes like sourdough discard crackers, banana bread, or quick flatbreads to add tang and improve texture.
How do I know if my hydration percentage is correct?
A 100% hydration starter has equal parts flour and water by weight, creating a thick but pourable consistency. If your starter is too runny, lower the percentage to 80%. If it is too stiff and cracks on top, increase it to 110–120% to match your kitchen's humidity and flour absorption rate.
Additional Guidance
Establish a consistent feeding schedule that aligns with your baking routine. If you plan to bake on Saturday, feed your starter Friday evening so it peaks during your morning mix. Keep a simple logbook or digital note tracking feeding dates, hydration levels, and ambient kitchen temperature, as warmer environments accelerate fermentation. Over time, you will notice how different flours and ratios affect your starter's rise time, allowing you to fine-tune your process for reliable, bakery-quality results at home.