Sourdough Starter Feeding Calculator
Calculate exact flour/water weights and estimate peak ripeness time.
Flour Needed
Water Needed
Total Yield
Estimated Time to Peak (Ripeness)
* Peak time assumes a healthy, active starter at 100% hydration. © Toolriz.com.
Sourdough Starter Feeding Ratio Calculator: Perfect Your Bake
Baking sourdough is as much a science as it is an art. One of the most critical steps in the process is feeding your sourdough starter. Getting the math wrong can lead to a sluggish starter, overly acidic dough, or a collapsed loaf. The Sourdough Starter Feeding Ratio Calculator by Toolriz.com is an ultra-advanced tool designed to take the guesswork out of your baking. It instantly calculates the exact grams of flour and water you need based on your desired ratio, and even estimates the peak ripeness time based on your kitchen's ambient temperature.
Whether you are maintaining a small 10g jar on your counter or building a massive 200g levain for a weekend bake, this calculator ensures your wild yeast is perfectly fed, active, and ready to leaven your bread.
How to Use the Sourdough Feeding Calculator
Using our calculator takes seconds. Follow these steps to dial in your starter:
- Select a Preset or Enter Custom Ratios: Use the quick buttons for standard 1:1:1, 1:2:2, or 1:5:5 ratios. Alternatively, manually enter your desired flour and water ratios (e.g., 1:3:3).
- Enter Starter Amount: Input the amount of unfed starter (in grams) you currently have in your jar.
- Enter Room Temperature: Input the current temperature of your kitchen in Fahrenheit. This is crucial for estimating when your starter will reach its peak.
- Review Your Results: The calculator will instantly show you the exact grams of flour and water to add, your total yield, and the estimated time it will take for the starter to peak and be ready for baking.
Understanding Sourdough Feeding Ratios (1:1:1 vs. 1:5:5)
A sourdough feeding ratio is expressed as Starter : Flour : Water. A 100% hydration starter means the flour and water weights are always equal. However, the amount of starter you keep compared to the fresh flour you add dramatically changes how the yeast behaves.
| Ratio | Yeast Behavior | Best Used For |
|---|---|---|
| 1:1:1 | Very fast fermentation. Peaks quickly and runs out of food fast. | Daily counter maintenance. Great for establishing a new, sluggish starter. |
| 1:2:2 | Standard pace. Balances yeast growth and acid development. | Standard daily feeding and preparing for a weekend bake. |
| 1:5:5 | Slow, steady fermentation. Extends the time before it peaks. | Building a levain overnight, or feeding before storing in the fridge. |
When you use a higher ratio like 1:5:5, you are essentially "diluting" the acid and giving the yeast a massive amount of fresh food. This forces the yeast to take longer to multiply and consume the sugars, which extends the peak time. This is why bakers use 1:5:5 or 1:10:10 when they want an overnight starter to be perfectly ripe at 8:00 AM the next morning.
How Temperature Affects Sourdough Peak Time
Wild yeast and lactic acid bacteria are highly sensitive to temperature. The Toolriz calculator uses a biological Q10 algorithm to estimate your peak time. Here is the general rule of thumb:
- Warm Kitchens (78°F - 82°F): Yeast activity speeds up drastically. A 1:5:5 feeding might peak in just 6-8 hours instead of 12. You risk over-fermenting and getting a "hooch" layer if left too long.
- Ideal Kitchens (70°F - 75°F): The sweet spot for sourdough. Steady, predictable fermentation.
- Cool Kitchens (60°F - 68°F): Yeast slows down. A 1:1:1 feeding might take 8-10 hours to peak. You may need to find a warmer spot in your house, like near the oven or on top of the refrigerator.
Why You Should Weigh Your Starter (Not Use Cups)
If you are still measuring your flour and water with measuring cups, you are setting yourself up for failure. A cup of flour scooped tightly can weigh 140g, while a cup scooped lightly can weigh 110g. That 30g difference is enough to ruin your hydration calculations for an entire loaf of bread.
Always use a digital kitchen scale that measures in grams. The Toolriz calculator outputs strictly in grams because sourdough baking requires 100% precision. A 1:1:1 ratio means if you have 20g of starter, you add exactly 20g of flour and 20g of water. No guessing, no volume conversions.
Frequently Asked Questions (AEO Section)
How do I calculate a 1:5:5 sourdough feeding ratio?
To calculate a 1:5:5 feeding ratio, you take the weight of your current starter and multiply it by 5 to get the amount of flour needed, and multiply it by 5 to get the amount of water needed. For example, if you have 20g of starter, you would add 100g of flour and 100g of water, yielding a total of 220g of starter.
How do I know when my sourdough starter has peaked?
A starter has reached its peak when it has doubled (or sometimes tripled) in size, is full of visible bubbles throughout the jar, and has a dome-shaped top. If you drop a teaspoon of it into a glass of room-temperature water and it floats, it is at peak activity and ready to bake with. Once it starts to deflate and sink, it has passed its peak.
What happens if I feed my starter too late?
If you wait too long to feed your starter, the yeast will consume all the available sugars and begin to run out of food. The starter will collapse, smell intensely like acetone or nail polish remover, and a layer of dark liquid (called hooch) will form on top. While not dangerous, baking with an over-fermented starter will result in a very sour, dense loaf of bread.
Can I feed my sourdough starter different types of flour?
Yes. While unbleached all-purpose flour and bread flour are standard, you can feed your starter whole wheat, rye, or einkorn. Rye and whole wheat contain more nutrients and minerals, which can boost yeast activity. Just be aware that whole grains absorb more water, so if you switch entirely to whole wheat, you may need to add a few extra grams of water to maintain 100% hydration.
Disclaimer: Toolriz.com is not a culinary school. Peak times are estimates based on standard yeast biological activity. Results may vary depending on the specific flour used, water hardness, and the unique microbiome of your local starter. Always use visual cues (doubling in size, float test) to confirm readiness.