# Baking 101: baker's percentages

Baker’s percentages are universally used by both professional and home bakers across the world. It is a very simple notation of writing down recipes in a scalable way so that the same formula can be used to bake a single loaf or a whole factory batch to feed the nation.

Even though it is a very simple and effective tool I’ve noticed that many home bakers struggle to understand how to use it. And then there are some bloggers who interpret baker’s percentages in a wrong way which only leads to more confusion.

Let’s take a look at what baker’s percentages really are and how to use them to bake existing recipes, adapt them and change them to your liking. I believe that once this tool is properly understood one can not only follow instructions, but also start creating their own breads.

Let’s take a look at Vermont Sourdough formula from the book Bread by Hamelman.

Rightmost column shows percentages. Formula also shows all the ingredients used in the recipe. What some people find confusing is that pre-ferments (sourdough, levain, poolish, biga, etc) are not shown in the formula. The reason behind this is that pre-ferments are NOT ingredients! They are dough development stages. There can be other stages as well, like scalds, sponges, etc. And neither of them is in the ingredient list in the formula. Another important observation is that baker’s percentages (or formula) don’t describe the method, they are only a part of the story.

## Formula structure

Baker’s percentages are calculated against overall flour content in the recipe. All types of flour combined should sum up to 100%. That obviously includes flour inside the starter if used, as well as alternative flours like oat flour or malt. Vermont Sourdough contains two flours: bread flour (90%) and whole rye flour or dark rye flour (10%). 90% + 10% = 100%.

All other ingredients are calculated as a percentage from overall flour content. In the example above salt is specified at 1.9%. You can easily see that if baking 10 kg of flour then 190 g of salt should be added. If baking 20 lb of flour then 0.38 lb of salt should be added. And if you want to bake a smaller loaf from 500 g of flour then you will only need 9.5 g of salt.

It’s time for yet another important observation - weight units do not matter when using percentages. You can bake the same bread using metric system or Imperial system. Or any other weight units you might imagine if needed. But please note that American way of using cups won’t work. Cups don’t measure weight, cups measure volume instead. Always use weight units to measure weight!

## Hydration

Bakers often talk about hydration which is a very important property of the dough. Hydration is the percentage of all liquids calculated against flour content. Baker’s percentages are usually specified without hydration thus it must be calculated manually.

Some recipes might have liquids which are not water: beer, milk, etc. Some recipes might have multiple source of hydration combined together. Final dough hydration is a sum of all of them. Please also note that water in the starter also counts towards dough hydration.

As you can see, Hamelman’s recipe has 65% hydration. If it had 45% water and 20% beer it would still be 65% hydration since 45% + 20% = 65%.

Some wet ingredients do not count towards hydration though as they don’t behave like water. Oils don’t really hydrate the flour and honey is too thick to be accounted for.

## Calculating correct values

I hope my readers are able to calculate basic arithmetic (addition, subtraction, multiplication and division), so let’s calculate ingredient requirements for Vermont Sourdough for an arbitrary total flour weight of 543 grams.

Bread flour should be 90% of 543 grams: 543 * 90 / 100 = 488.7 g.

Rye flour should be 10%: 543 * 10 / 100 = 54.3 g.

Water should be 65%: 543 * 65 / 100 = 352.95 g.

And salt should be 1.9%: 543 * 1.9 / 100 = 10.317 g.

Super simple, right? Changing formula to suit your needs is super simple too. For example, you might want to bump up hydration to 70%. Everything else stays the same, you only re-calculate water: 543 * 70 / 100 = 380.1 g. Or you might want to replace 10% of rye with 20% of whole wheat. Now your bread flour will become 80% and whole wheat will 20%. Do some simple math and you will get a new recipe in less than a minute!

## Starters and pre-ferments

As was said above, pre-ferments of all kinds are not ingredients. Thus their contents count towards overall flour and water content. That has several consequences.

First of all, stating that recipe has 15% sourdough doesn’t make any sense. The weight of sourdough will depend on its hydration and since sourdoughs vary wildly from 50% to 200% hydration adding 15% of it will yield completely different result.

Flour content and hydration will change noticeably too. For example, you want to bake a bread with 1000 g of flour and 15% of sourdough. 15% from 1000 g is 150 g. 150 g of sourdough with 50% hydration will have 100 g of flour and 50 g of water. That will make your overall flour amount to become 1150 g instead of 1000 g. On the other hand 150 g of 200% hydration sourdough will have only 50 g of flour and 100 g of water. That will increase your overall flour amount slightly, but will increase your hydration a lot. And if you want to use 30-50% of sourdough everything will get skewed even more.

Correct way to address this issue is to use multi-stage approach as shown in all recipes in my blog and in good bread baking books. Pre-ferments are never ingredients, so instead of adding X% of sourdough you should pre-ferment Y% of flour.

Let’s use the same recipe and the same total flour amount of 543 grame and let’s pre-ferment 15% of flour at 100% hydration. And we will use bread flour for that exclusively.

15% is 543 * 10 / 100 = 81.45 g. We will need the same amount of water to get to 100% hydration, so overall sourdough weight will be 81.45 + 81.45 = 162.9 g. We should subtract 81.45 g from overall bread flour weight (488.7 - 81.45 = 407.25 g of bread flour will be added to the final dough) and the same 81.45 g from water (352.95 - 81.45 = 271.5 g of water will be added to the final dough).

Now we can use Sourdough Calculator to calculate how much starter we need and how much fresh flour and water should be added. With a 1:9 inoculation rate we will need 16.29 g of 100% hydration starter, 73.305 g of fresh bread flour and 73.305 g of water and it will be ready in about 12 hours. We can now also change inoculation rate to make our sourdough faster or slower to fit into our busy lives yet the baker’s formula will remain the same and the bread will remain the same.

At this point in time we have reverse engineered Hamelman’s recipe by only knowing its baker’s formula. Author is using different pre-ferment ratio, but the end result is close enough for an exercise. Now we can write it down with final weight values the following way:

Using multi-stage approach also opens up more complex breads to us. Now you can adjust the process to pre-ferment X% of flour with a sourdough and Y% with a poolish and then scald Z% of flour. I will be writing about staged approach in the near future.

## Conclusion

Baker’s percentages or baker’s formula is a great and easy to use tool to scale and modify bread recipes. It might be a bit tricky to get your head around it at first, but once you understand it you will be able to do a lot more with just a few ingredients. You can bake multiple different breads using the same three-four ingredients in different ratios and applying different dough development stages and you can also easily adjust existing recipes to suit your needs and taste.

The best way to understand how it all works is to simply take one solid recipe from a well known book with a formula provided, take a pen with paper and do some basic maths yourself. I believe everyone should become comfortable after just a few tries.