Sourdough Calculator

Baker's percentages explained

Bakers express every ingredient as a percentage of the total flour weight, with flour fixed at 100%. A dough with 1,000 g of flour, 700 g of water and 20 g of salt is 100% flour, 70% water (hydration) and 2% salt. Because the percentages do not depend on batch size, a formula written this way scales instantly to one loaf or twenty.

Why the starter changes hydration

A starter is just flour and water. If you ignore it, you will underestimate how wet your dough is. Take a recipe with 500 g flour, 350 g water, 100 g of 100%-hydration starter and 10 g salt. It looks like 70% hydration, but the starter adds 50 g flour and 50 g water: total flour is 550 g, total water 400 g, so the true hydration is 400 ÷ 550 = 72.7%. Salt is 10 ÷ 550 = 1.8%. The calculator always reports the true figure.

Designing a recipe from a target loaf

For a 900 g loaf at 75% hydration with 20% starter and 2% salt: total flour = 900 ÷ (1 + 0.75 + 0.02) ≈ 508 g. Starter is 20% of that ≈ 102 g, which at 100% hydration contains about 51 g each of flour and water. So you add about 458 g flour, 331 g water and 10 g salt. The finished dough weighs about 900 g before baking; expect it to lose roughly 10–20% of its weight in the oven as water evaporates.

Choosing a hydration

Whole wheat and rye flours absorb more water than white flour, so a 30% whole wheat dough at 75% feels similar to a white dough at about 70%. Start lower with a new flour and increase hydration by a few percent each bake.

Starter (levain) amount and timing

The more starter you use, the faster the dough ferments. Higher starter percentages (20–25%) suit cooler kitchens or a same-day bake; lower ones (5–10%) slow fermentation, which is useful in warm weather or for an overnight bulk ferment. Temperature matters as much as quantity: at around 24–26 °C (75–78 °F) a dough with 20% starter often finishes bulk fermentation in roughly 4–6 hours, while the same dough in a cool kitchen can take much longer. Watch the dough, not the clock – look for a 50–75% rise, a domed surface and bubbles at the sides of the container.

Feeding ratios for your starter

Feeding ratios are written starter : flour : water by weight. At 1:1:1, 30 g starter is fed 30 g flour and 30 g water; it usually peaks in a few hours at room temperature. At 1:5:5, the same starter gets 150 g of each; the extra food means it peaks much later – handy if you want to feed it at night and use it in the morning. The calculator works backwards from the amount of levain your recipe needs and adds a small buffer, because some always sticks to the jar.

A basic sourdough schedule

1. Feed your starter and wait until it peaks (doubled, domed, full of bubbles).
2. Mix flour and most of the water; rest 30–60 minutes (autolyse) if you like.
3. Add the starter, salt and remaining water; mix until combined.
4. Bulk ferment, with 3–4 sets of stretch-and-folds in the first couple of hours.
5. Pre-shape, rest 20–30 minutes, then shape and place in a floured basket.
6. Proof at room temperature, or cold-retard in the fridge overnight for more flavour and easier scoring.
7. Bake in a preheated Dutch oven, covered for about 20 minutes and uncovered until deep brown.

Troubleshooting

• Dense, tight crumb: under-fermented – extend bulk fermentation or keep the dough warmer.
• Flat loaf that spreads: over-fermented or too wet for the flour – shorten bulk, lower hydration or build more strength with folds.
• Very sour: long cold fermentation or a starter fed infrequently – use a younger starter or a shorter retard.
• Gummy centre: underbaked or cut too soon – bake to an internal temperature of about 96–99 °C (205–210 °F) and cool at least an hour.

Scaling a recipe up or down

To make two loaves instead of one, multiply every ingredient by 2; for a smaller loaf, multiply by a fraction. Because the calculator works in baker's percentages, you can also enter a total dough weight instead – for example 1,800 g for two 900 g loaves – and it recalculates every ingredient. Bulk fermentation time does not double with a larger batch; a bigger mass of dough holds its temperature better, so it may even ferment slightly faster.

Adding whole grains, seeds and inclusions

• Whole wheat, spelt and rye: start by replacing 10–30% of the white flour and raise hydration by a few percent, because bran absorbs more water.
• Seeds and grains: soak them first (a 'soaker') in roughly their own weight of water, so they do not pull water from the dough; add them during the first set of folds.
• Cheese, olives, nuts and dried fruit: commonly about 10–30% of the flour weight; add them during folds and pat dry wet ingredients.
• Inclusions are usually left out of baker's-percentage hydration, but the calculator lists them so the total dough weight is right.

Converting a yeasted recipe to sourdough

A simple starting point is to remove the commercial yeast and add 15–20% active starter (by total flour weight), then reduce the recipe's flour and water by the amounts inside the starter so the hydration stays the same. Expect bulk fermentation to take several hours longer than the yeasted version, and use the dough's rise and feel – not the original recipe's times – to judge when it is ready.

Looking after your starter

A starter kept at room temperature is usually fed once or twice a day; one kept in the fridge can go about a week between feeds. Before baking, take it out and give it one or two feeds at room temperature so it is lively. 'Discard' – the starter you remove before feeding – can go into pancakes, crackers or flatbreads. A layer of grey liquid ('hooch') on top means the starter is hungry; pour it off or stir it in, and feed it.

Temperature and desired dough temperature

Many bakers aim for a dough temperature of about 24–26 °C (75–78 °F) after mixing. A simple way to hit it is to adjust the water temperature: use warmer water on a cold day and cooler water on a hot one. A cheap probe thermometer makes fermentation far more predictable than following times in a recipe.

Common hydration mistakes

• Forgetting the starter's water, which makes a recipe wetter than it looks – the main reason doughs feel stickier than expected.
• Copying a high-hydration recipe written for strong bread flour while using all-purpose flour, which absorbs less water.
• Adding all the water at once to a new flour; hold back about 5–10% and add it only if the dough feels stiff ('bassinage').
• Measuring by cups: a cup of flour can vary by 20% or more in weight depending on how it is scooped.