Baker's percentages let you rescale, compare and diagnose any recipe

What follows is the working version of reading recipes in baker's percentages: the decisions in the order you actually meet them, with the reasoning attached.

The convention

In baker's percentages, the total flour weight is defined as 100 per cent and every other ingredient is expressed against it. So a dough with 1000g flour, 700g water, 20g salt and 200g starter is 70 per cent hydration, 2 per cent salt and 20 per cent starter.

The percentages add up to more than a hundred, which looks wrong the first time and is entirely standard. When several flours are used, they are counted together as the 100 per cent and each is also listed individually. The whole point is that flour is the reference against which every other decision is made.

Rescaling without arithmetic errors

To scale a recipe, decide the flour weight you want and multiply every percentage by it. Wanting 600g of flour instead of 1000 means simply recalculating from the same percentages, with no ratios to invert.

This is far less error-prone than multiplying every line of a recipe by 0.6 and rounding as you go. It also scales cleanly to any tin size once you know how much dough your tin takes. Bakeries work this way for exactly this reason, and it transfers directly to a home kitchen.

Comparing recipes

Two recipes with different yields cannot be compared by looking at the ingredient lists. Converted to percentages, it becomes immediately obvious that one is 65 per cent hydration and the other 78.

The dough tells you first: you can see at a glance whether a recipe is enriched, how much preferment it uses and whether the salt is high or low. This is how you work out why one recipe you liked behaved differently from another you did not. Ten minutes converting your favourite recipes teaches you more than reading a dozen new ones.

Counting hidden flour and water

A preferment or a starter contains both flour and water, and both must be counted in the totals. A 200g starter at equal flour and water contributes 100g to each side, which shifts the hydration noticeably.

Milk is roughly ninety per cent water, eggs about seventy five, and butter around sixteen per cent water. Ignoring these is why enriched doughs so often behave much wetter or drier than their stated hydration suggests.

Writing the full calculation once for a recipe you bake often is worth the fifteen minutes.

Using it to diagnose

If a dough is unmanageably slack, checking the true hydration usually explains it before you blame technique. If bread tastes flat, checking the salt percentage takes ten seconds and often finds the problem. If a loaf ferments unpredictably, the preferment percentage tells you how much of the flour arrived pre-fermented.

Percentages turn vague impressions into specific numbers you can change one at a time. That is the difference between adjusting a recipe and guessing at it.

Flour absorbs water differently by brand and by season; hydration is a target, not a rule.

Where it does not fit

Cake recipes are sometimes written this way, but with sugar or egg often exceeding the flour weight the intuition is less useful. Very enriched doughs can reach percentages that look alarming, such as 50 per cent butter in brioche, without anything being wrong.

Pastry is usually described by simple ratios instead, such as two parts flour to one part fat. None of that reduces the value of the system for bread, where it is close to essential. Use it where it clarifies and ignore it where it does not.

The takeaway

Convert your three favourite recipes to percentages and you will understand all three better by lunchtime.

Patience is an ingredient, and it is the one people leave out.