Sourdough Discard Ratio Calculator

How to Use This Tool

Follow these simple steps to calculate your sourdough discard ratios:

1. Enter your desired total dough weight in the input field, and select grams or ounces as your unit.
2. Choose your sourdough discard’s hydration percentage from the dropdown (100% is standard for most fed starters).
3. Input the discard proportion: the percentage of total flour that will come from your discard (30% is a common default for many discard recipes).
4. Click the Calculate Ratios button to see your detailed results.
5. Use the Reset button to clear all inputs and start over, or Copy Results to save your calculations.

Formula and Logic

This calculator uses standard sourdough baking math to ensure consistent results:

• Discard hydration is defined as (water weight / flour weight) * 100, so 100% hydration means equal parts flour and water by weight.
• Total flour in the dough is calculated as dough weight / (1 + (hydration percentage / 100)) to account for both flour and water content.
• Discard flour contribution is determined by multiplying total flour by your discard proportion percentage.
• Discard weight is derived from its flour contribution and hydration ratio, then added flour and water are calculated to reach your target dough weight and hydration.

All calculations are done in grams first for precision, then converted to your selected unit (grams or ounces) for output.

Practical Notes

These real-world tips will help you get the most out of your sourdough discard baking:

• Most home sourdough starters are 100% hydration (fed with equal parts flour and water by weight), so use this setting unless you know your discard has a different ratio.
• Discard proportion of 20-40% is typical for recipes like pancakes, waffles, and quick breads, while higher proportions work for rustic loaves.
• Weigh ingredients with a digital scale for best results—volume measurements (cups) are less precise for sourdough baking.
• Using discard instead of active starter saves time, as you don’t need to feed or wait for your starter to peak before baking.
• Store discard in an airtight container in the fridge for up to 1 week, or freeze for up to 3 months to reduce food waste.

Why This Tool Is Useful

Home bakers benefit from this calculator in several ways:

• Eliminates guesswork when substituting discard for active starter in recipes, reducing failed bakes.
• Scales recipes up or down easily for small batches or large family meals.
• Helps use up excess discard instead of throwing it away, saving money and reducing food waste.
• Ensures consistent hydration across batches, so your baked goods turn out the same every time.

Frequently Asked Questions

Can I use volume measurements (cups) instead of weight?

Weight measurements (grams or ounces) are strongly recommended for sourdough baking, as volume measurements vary based on how tightly ingredients are packed. This calculator only supports weight units to ensure accuracy, but you can convert cups to grams using standard conversion charts (1 cup all-purpose flour ≈ 120g, 1 cup water ≈ 240g).

What if my discard is older than 1 week?

Older discard (up to 2 weeks in the fridge) is still safe to use, but may have a more sour flavor. Very old discard may lose its leavening power, so it’s best used in recipes that rely on baking soda or baking powder for rise rather than the discard itself.

How do I adjust the recipe for high altitude baking?

High altitude baking may require slightly less water or more flour, as lower air pressure causes liquids to evaporate faster. Reduce water by 5-10% or add 1-2 tablespoons of extra flour at a time until the dough reaches your desired consistency.

Additional Guidance

For best results when using sourdough discard:

• Let cold discard come to room temperature for 30 minutes before mixing to ensure even incorporation.
• Adjust the discard proportion based on the recipe: delicate baked goods like cakes work best with lower discard proportions, while hearty breads can handle higher ratios.
• Keep a discard jar in your fridge and add to it after every feeding, so you always have discard on hand for impromptu baking.
• Label your discard jar with the date it was started to keep track of freshness.