Sourdough discard recipe converter

Enter the flour and liquid of any recipe and the discard you want to use. You see how much flour and liquid to leave out so the dough stays the same.

Result

Flour to use

250 g

Liquid to use

150 g

Show in

What the result is made of, by weight

Flour to use 50 %
Liquid to use 30 %
Flour in the discard 10 %
Water in the discard 10 %

Step by step
Flour in the discard = discard ÷ (1 + hydration)	50.0 g
Water in the discard = discard − its flour	50.0 g
Flour to use = recipe flour − discard flour	250.0 g
Liquid to use = recipe liquid − discard water	150.0 g
Total flour in the dough	300.0 g
Total liquid in the dough	200.0 g
Hydration of the original recipe	66.7 %
Hydration with the discard	66.7 %

How it works

Discard is flour and water. The calculator splits your discard by its hydration and takes the same amount of flour and liquid out of the recipe, so the dough keeps its original balance.

Formula

Discard flour = D ÷ (1 + h). Discard water = D − discard flour. Flour to use = F − discard flour. Liquid to use = L − discard water. Neither goes below zero; any excess is shown separately.

Worked example

The calculator opens with this example; the result above is computed from it.

Input	Value
Flour in the recipe	300 g
Liquid in the recipe	200 g
Discard to use	100 g
Discard hydration	100 %
Flour to use	250 g
Liquid to use	150 g

100 g of discard at 100 % holds 50.0 g of flour and 50.0 g of water. Use 250 g of flour instead of 300 g and 150 g of liquid instead of 200 g.

Assumptions and limits

Milk and other thin liquids are counted like water. Eggs, butter and oil are not changed.
All amounts are weights. Cups and spoons are not accurate enough for this.
The discard is assumed to have the hydration you feed your starter at.
Discard adds sourness and some leavening; the maths only keeps flour and liquid in balance.

The result is an estimate for planning, not professional advice.