How much starter do I need for 500 g of flour?

At the standard 20% levain, 100 g of starter. In a cool kitchen, 25% (125 g) gives fermentation a push; for a long cold retard you can drop to 15%.

What hydration should sourdough be?

70% of flour weight is a forgiving default for a home loaf, and 75–80% gives a more open, airy crumb at the cost of stickier handling. What matters is true hydration — after the water inside the starter is counted.

How does starter affect dough hydration?

A 100%-hydration starter is half flour and half water, so each gram adds 0.5 g of water and 0.5 g of flour. On the default formula that raises true hydration from 70% to about 72.7%, which is why this calculator splits the starter out.

How much salt per 100 g of flour?

Two grams — the standard 2% baker’s percentage. It strengthens gluten and keeps fermentation orderly; much above 2.5% and the starter starts to slow noticeably.

What is inside a 100% hydration starter?

Equal weights of flour and water — 50 g of each in a 100 g starter. It is built and maintained with 1:1:1 feeds: one part ripe starter, one part flour, one part water by weight.

What are typical baker’s percentages for sourdough bread?

Flour 100%, water 68–75%, starter 15–25%, salt 2%. Percentages let you scale the same loaf to any flour weight, which is exactly what the fields above do.

Sourdough Starter Calculator | Online Calculators Free

The sourdough formula

A standard loaf is anchored on flour at 100% with water at about 70%, starter at 20%, and salt at 2%. Enter any flour weight and the calculator scales everything else: 500 g of flour means 350 g of water, 100 g of starter, and 10 g of salt.

True hydration counts the starter

A 100%-hydration starter is half flour and half water by weight, so it drags both into the dough. In the default formula the starter adds 50 g of flour and 50 g of water, lifting true hydration from the recipe’s 70% to 72.7%. Ignoring this is why doughs sometimes feel stickier than the formula promised.

Salt and starter amounts

Salt at 2% of flour is the sourdough standard — 2 g per 100 g of flour — enough to tighten gluten and moderate fermentation without slowing the starter too much. Starter percentage rises toward 25% in cool kitchens where fermentation needs a push, and drops for long, cold retardes.

Worked example

Bake the classic 500 g flour, 70% hydration, 20% starter.
Weigh 350 g water, 100 g starter, 10 g salt.
The starter contributes 50 g flour + 50 g water.
True hydration: 400 ÷ 550 = 72.7% — 960 g of dough, 1.3 loaves.

How to use it

Enter the flour weight for the batch you want.
Set water, starter, and salt as percentages of that flour.
Leave starter hydration at 100% unless you keep a stiff or wet starter.
Weigh each row, and use the maintenance-feed ratio for the starter itself.