Discard is the one ingredient where cup measurements genuinely misbehave, because it's a viscous, aerated, semi-liquid mixture whose density changes depending on how recently you stirred it. This page is the reference table.

The conversions

For a standard 100%-hydration starter (fed equal weights flour and water):

| Volume | Weight | Contributes | |---|---|---| | 1 tablespoon | ~15g | 7.5g flour + 7.5g water | | ¼ cup | ~60g | 30g flour + 30g water | | ½ cup | ~120g | 60g flour + 60g water | | ¾ cup | ~180g | 90g flour + 90g water | | 1 cup | ~240g | 120g flour + 120g water | | 2 cups | ~480g | 240g flour + 240g water |

One cup of discard weighs roughly 240g. That is a convenient coincidence — it's about the same as a cup of water — and it holds because 100% hydration discard is roughly half flour and half water by weight, and the flour's greater density is offset by the air stirred through it.

Why your cup might weigh 210g, or 265g

All of these move the number, and none of them are mistakes:

  • How recently you stirred. A freshly stirred discard has air folded through it and weighs less per cup. Discard that's been sitting undisturbed for a week is denser.
  • How risen it is. Discard caught shortly after a feed is full of gas. Truly hungry, collapsed discard packs tighter.
  • Whether you spooned or poured. Pouring traps less air than spooning does.
  • Temperature. Cold discard from the fridge is stiffer and holds its air structure; room-temperature discard slumps and settles.

A 10% swing either way is completely normal. In a pancake batter it is invisible. This is the argument for weighing, if you have scales — not because precision matters much in these recipes, but because it removes a variable when something doesn't come out as expected.

Hydration: what it changes

Starter hydration is the weight of water as a percentage of the weight of flour. Fed 100g flour and 100g water, that's 100% hydration. Fed 100g flour and 75g water, that's 75%.

Most home starters are 100%, because it's the easiest to feed — equal weights, no thinking. If you've never deliberately made yours stiffer, it's 100%.

Hydration changes what a given weight of discard contributes:

| Hydration | 100g discard contains | Texture | |---|---|---| | 100% (typical) | 50g flour + 50g water | Pourable, like thick batter | | 75% | 57g flour + 43g water | Thick, spoonable | | 60% | 62g flour + 38g water | Stiff, dough-like |

The general formula: flour = weight ÷ (1 + hydration), with hydration as a decimal. Water is whatever's left. At 100%, 100 ÷ 2 = 50g flour, and the other 50g is water.

This only matters when you're adapting a recipe and need to subtract the discard's contribution from the recipe's own flour and liquid — which is covered step by step in how to put discard into any recipe.

Cups by weight, for the recipes on this site

Every edition on this site gives both. For reference, the flour and liquid figures we use:

| Ingredient | 1 cup | |---|---| | All-purpose / plain flour | 120g | | Wholemeal flour | 128g | | Water or milk | 240g | | Granulated sugar | 200g | | Olive oil | 216g |

Flour is the one worth weighing if you weigh nothing else. A cup of flour scooped straight from the bag can be 150g rather than 120g — a 25% error, which is enough to turn a batter into a dough and is the single most common reason a recipe "doesn't work".

A note on the ratios you'll see quoted

You'll find recipes describing a starter as "1:1:1" or "1:2:2". Those are feeding ratios — starter to flour to water, by weight. A 1:1:1 feed means 50g starter, 50g flour, 50g water. A 1:5:5 feed is a much smaller proportion of old starter, so it ripens more slowly and tastes milder.

Feeding ratio changes how fast your starter ripens and how sour it gets. It does not change the conversions on this page, as long as the flour and water in the feed are equal — the discard is still half flour, half water whatever ratio produced it.

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