Baker’s percentages explained: flour as 100%, hydration and scaling

Baker's percentages express every ingredient as a percentage of the flour weight, and the flour always counts as 100%. A loaf of 500 g flour and 350 g water is therefore 70% water, whatever the batch size. That makes recipes easy to compare, scale and adjust, and it is why bakers talk about "a 70% dough". The baker's percentage calculator converts any recipe to percentages and rescales it, and this guide explains the method.

The one rule

Divide each ingredient's weight by the total flour weight and multiply by 100. If a recipe uses more than one flour, such as white and wholemeal, add them together: the total flour is 100%, and each flour is its own share of it. Everything else, including water, salt, yeast, sugar, butter and seeds, is a percentage of that total. Because the percentages are relative to flour, they do not add up to 100. A typical lean bread adds up to about 170 to 175%, and the total percentage is useful in its own right for scaling. The method only works with weights, so use a scale, not cups.

A worked example

Take a basic loaf of 500 g bread flour, 350 g water, 10 g salt and 7 g instant yeast:

• Flour: 500 ÷ 500 = 100%
• Water: 350 ÷ 500 = 70%
• Salt: 10 ÷ 500 = 2%
• Yeast: 7 ÷ 500 = 1.4%

The total is 867 g, or 173.4%. Laid out like this, you can see at a glance that the salt is at the usual 2% and the yeast is on the generous side for a long rise. A common basic formula is 100% flour, around 60% water, 2% salt, 1% yeast and 1% fat, and most bread recipes are variations on it.

What hydration tells you

The water percentage is called hydration, and it predicts how a dough will behave. Stiff doughs at roughly 50 to 57% suit bagels and pretzels; 58 to 65% is typical for sandwich breads and rolls; 70 to 75% gives rustic loaves with a more open crumb; 80% and above is ciabatta and open sourdough territory, slack and sticky to handle. Flours absorb differently, so the same hydration feels wetter with soft white flour and stiffer with wholemeal, which soaks up more water. Other liquids count too, but only partly: milk is mostly water, so 300 g of milk adds about 260 g of water, while butter and eggs contribute less. The calculator lets you tick which ingredients count as liquid, but treat hydration with milk, eggs or butter as approximate.

Scaling a recipe

To make a target amount of dough, divide the target weight by the total percentage (as a decimal) to get the flour, then multiply the flour by each percentage. For eight 80 g rolls you need 640 g of dough: 640 ÷ 1.734 gives about 369 g flour, then 258 g water, 7.4 g salt and 5.2 g yeast. To make about 1 kg from the same formula, the flour becomes about 577 g and the water about 404 g. Add a few per cent extra to cover dough left on the bowl and bench. Pizza works the same way: four 250 g balls at 62% water, 2% salt and 0.5% yeast need about 608 g flour, 377 g water, 12 g salt and 3 g yeast; the pizza dough calculator has style presets for that. For recipes written in cups and servings rather than weights, the recipe scaler is the better tool, and Ratios explained: how to simplify, scale, and divide an amount in a given ratio covers the arithmetic of scaling.

Sourdough starter and preferments

A sourdough starter or a preferment such as a poolish contains flour and water of its own, and honest percentages count them. A starter at 100% hydration is half flour and half water, so 100 g of starter adds 50 g of each. A dough of 400 g flour, 280 g water, 100 g starter and 8 g salt looks like 70% hydration, but the true totals are 450 g flour and 330 g water, which is 73.3%, with salt at 1.8%. That difference explains why a recipe can feel wetter than its numbers suggest. The sourdough calculator folds the starter into the totals automatically. Yeast type changes the weight you need too: instant, active dry and fresh yeast are not interchangeable gram for gram, and the yeast converter swaps between them.