Half a cup of sourdough discard is about 113 grams, and one cup is about 227 grams. If you’re holding a sticky measuring cup over the sink, the scale is the easier option.
Use the calculator above to convert your amount and see how much flour and water it contains. The cup conversion assumes a stirred starter; the flour-and-water calculation assumes 100% hydration, or equal weights of each.
Sourdough discard cups to grams
| US volume | Approximate discard weight |
|---|---|
| 2 tablespoons | 28 g |
| 1/4 cup | 57 g |
| 1/3 cup | 76 g |
| 1/2 cup | 113 g |
| 2/3 cup | 151 g |
| 3/4 cup | 170 g |
| 1 cup | 227 g |
| 1 1/2 cups | 341 g |
The starting point is King Arthur Baking’s starter conversion, which uses 227 grams for one cup. The other rows are proportional amounts rounded to a whole gram.
This is a practical conversion, not an exact density for every jar. A bubbly starter fills more space than the same starter stirred flat. When a recipe supplies its own gram weight, follow that weight.
How to weigh discard without another dirty cup
Put the mixing bowl on a scale, press tare, and add discard until the display reaches your target. Cold discard is fine to weigh; it just pours more slowly.
If the recipe calls for half a cup and supplies no weight, aim for 113 grams. If it says half a cup is 120 grams, use its stated 120 grams. The author has chosen a different volume conversion, and splitting the difference adds a variable you didn’t need.
Stir before measuring by cup so large bubbles don’t distort the amount. Stir before portioning from a separated jar too, so you’re taking a representative mixture of flour and water rather than mostly liquid from the top.
How much flour and water are in the discard?
For 100% hydration discard, divide its weight by two.
| Discard weight | Flour already present | Water already present |
|---|---|---|
| 50 g | 25 g | 25 g |
| 100 g | 50 g | 50 g |
| 113 g | 56.5 g | 56.5 g |
| 200 g | 100 g | 100 g |
| 227 g | 113.5 g | 113.5 g |
For example, adding 100 grams of this discard to a recipe contributes 50 grams of flour and 50 grams of water. Subtracting those from the recipe preserves the ingredient balance on paper, but acidity and fermentation still affect the result. It isn’t a promise that any cake or cookie recipe will behave the same.
A starter at another hydration needs different math: flour = discard weight ÷ (1 + hydration ÷ 100). Water is the remaining weight. A 150-gram starter at 50% hydration contains 100 grams flour and 50 grams water. The calculator above stays at 100% hydration deliberately.
Scale a recipe to the jar you have
Divide the discard you have by the amount the recipe requests. That’s your batch multiplier.
If you have 150 grams and the recipe needs 227 grams, the multiplier is about 0.66. Multiply the other ingredients by that number too. Don’t simply reduce the discard while keeping all the flour.
Eggs are the awkward part. Beat an egg, weigh it, and use the required fraction, or choose a recipe that fits a whole egg. Pan size and cooking time don’t scale in a straight line with ingredient weight.
Which recipe fits 113 or 227 grams?
With about 113 grams, make one skillet flatbread. It uses a small pan and doesn’t ask you to divide an egg.
With 227 grams, choose the pancake or cracker recipes, or the thin discard pizza crust. Pancakes take about 20 minutes; the crackers take about an hour plus cooling. Pick by both the jar and the clock.
Keep your discard covered in the refrigerator and label its collection date. Use a maintained, established starter, and discard a jar with mold, pink or orange discoloration, or a rotten smell. Weighing a questionable jar more precisely doesn’t make it usable.
