Baker's percentages and hydration

Bread formulas are written in baker’s percentages: every ingredient is given as a percentage of the total flour weight. Flour is always 100%.

ingredient % = ingredient weight ÷ flour weight × 100

Once you can read them, you can compare recipes at a glance and scale any of them.

A worked example

Ingredient	Weight	Baker’s %
Flour	500 g	100%
Water	350 g	70%
Levain	100 g	20%
Salt	10 g	2%
Total dough	960 g	192%

Hydration

Hydration is the water as a percentage of the flour. The dough above is “70% hydration”.

Strictly, the levain contains flour and water too. A levain fed with equal weights of each is half flour, half water, so 100 g of it adds 50 g to both sides:

total flour = 500 + 50 = 550 g
total water = 350 + 50 = 400 g
overall hydration = 400 ÷ 550 = 72.7%

Most recipes quote the simpler figure. It matters only when you compare formulas that use very different amounts of levain.

Hydration	What the dough is like
65–70%	Firm and easy to shape. A good place to start.
70–75%	Softer, slightly sticky. A more open crumb.
75–80%+	Slack and sticky. Needs practice and strong flour.

Wholemeal flour absorbs more water than white flour, so a wholemeal dough feels stiffer at the same hydration.

Typical ranges

• Salt: 1.8–2.2%. Less tastes flat; more slows fermentation.
• Levain: 10–30%. More levain ferments faster; less gives you a longer, slower schedule.

Scaling a formula

To make a dough of a chosen weight, divide that weight by the sum of the percentages, then multiply back.

For a 900 g dough with the formula above (192% in total):

flour  = 900 ÷ 1.92 = 469 g
water  = 469 × 0.70 = 328 g
levain = 469 × 0.20 =  94 g
salt   = 469 × 0.02 =   9 g

That adds up to 900 g. Dough loses roughly 10–15% of its weight in the oven, so a 900 g dough gives a loaf of about 770–810 g.