Monday, February 21, 2011

Hydration Percentages, Demystified

When I first started making bread, I read a lot of different bread blogs. One of the things I noticed was that people talked about the percentage of the hydration of the dough, but I had no idea what that meant and I had trouble finding a coherent explanation, even though I am sure they were right under my fingertips. I also thought using grams rather than volume measurements to weight the dough was a ridiculous waste of time. Now I know better.

The clearest explanation I have ever found comes from Lisa Rayner's Wild Bread, which I have discussed in previous posts (Rayner 56-57). First off, baking percentages are based on grams. They are not particularly useful if you are only using volume measurements (although if you're willing to do a lot of math it could help you out).

So flour is always considered to be 100%. Let's say that you are using 500 grams of flour for your recipe, 100% is 500g. Water, or "hydration percentage," is calculated by it's comparision to the flour. For example,  375g means that to get the "hydration percentage" you divides 375g/500g=75% hydration. At this point the bread itself is 175% hydration. For most breads, salt should be between 1.8-2%, therefore between 9-10g of salt.

As a note, this flour and water includes any flour and water in your poolish or your sourdough starter. For example, if you use 100% hydration sourdough starter (which is what I have, meaning that I feed it with equal parts flour and water), then you can divide the weight of your starter in half. For example, if you use 200 grams of sourdough starter at 100% hydration, this means you consider it in baker's percentages as 100g water and 100g flour. So if you were to add 200g starter to your 500g flour and 375g water, then your bread would be (375+100g water)/(500+100g flour)=79.1%. The overall dough was 180% (if we use 1.9% salt). This would be a very wet dough-- maybe a ciabatta or focaccia. Lean European white doughs are around 65% hydration and whole wheat lean doughs are closer to 75% (because whole wheat flour absorbs more water).
Wild Bread - Handbaked sourdough artisan breads in your own kitchen
Baking percentages are important because they allow you to easily scale the amount of loaves up or down. They also allow you to decide how to modify recipes based on changing recipes from regular yeast to sourdough starter. Rayner says making the starter equal 20-60% of the total recipe's flour and water, and then subtracting that amount of flour and water from the recipe (Rayner 57).

If you are interested in using volume measurements but are willing to do the math to use baker's percentages, I found this tool to convert flour. Also, for water, 1g=1ml and ml can be converted into other volume measurements.

Today, while I try to translate Horace, Medea, and do my math homework, I am making two recipes using weights (in grams) instead of volumes trying to increase my understanding of baker's percentages. Wish me luck!


  1. Sounds complicated, but I bet they will be delicious. Wish I could be your official taste tester! I'm thinking of making foccacia soon, since it's about the only bread I make.

  2. Not as complicated after I red it second time. Regarding the baker's percentages and conversions; Would it help if I made a handy converter/s for that? What measuring units would be involved for these percentages? ... E.g. from a first A unit into a second B unit measures. Please give me some clue/s so I can visualize the functions. In other words, how do you do the "math to use baker's percentages", what's involved? I will use it as well. So far I created 15 flour units converters. The Baker's Apprentice book by P.R. is always on my bed side table. Thank you.

    Flour units converters

    Warm regards,

  3. Glad it was helpful! If you want to use volumes instead of weight, the conversion sites online are great because they let you pick out the ingredient and then do all of the math for you. Also, of course, Peter Reinhart wonderfully does at least volume and ounces, and in his later books volume, ounces, and grams for every ingredient.

    If you want to use volumes for baking, conversion sheets are a great thing. I usually use Gourmet Sleuth, but it's a bit complicated. Here are some helpful thoughts:
    To make my favorite breakfast bread, I use:
    100g sourdough starter which is approximately 2/3 of a cup, depending upon your starter.
    350g whole wheat flour = just under 3 cups (2.197C)
    150g unbleached all-purpose flour = 1.2 cups
    400g water = 1.69 cups
    10g salt = 1 2/3 teaspoons
    1/6 cup toasted flax seeds
    1/6 cup steel cut oats

    All calculations for baker's percentages have to be made in weight rather than volume. So for the bread you calculate:
    (water weight total)/(flour weight total) = (50+400)/(50+150+350) = 82% approximately.
    The 50s on either side of the equation are for the equal parts of flour and water in my sourdough starter. This percentage changes if you consider the steel cut oats to be part of the flour because they absorb some water, but I am not taking that into consideration.

    Note: Peter Reinhart says that baker's dip the cup into the flour and level the top with a knife rather than pressing it in on the side of the flour bag. This changes the measurement.

    That said, I almost never use volume except for something like baker's yeast, honey, or olive oil. I have a handy digital scale that has a "tare" function on it so that I can measure the ingredients as grams in bowls or cups. I then combine those ingredients in a larger bowl as the directions suggest. I found this helps my cooking a lot because my measurements are more accurate and predictable. I also am a total nerd and I keep a calculator in the kitchen so that I can recalculate or check my calculations if need be.

    I hope that helped. If not I am happy to try to clarify. Good luck!

  4. I forgot to post my links! oops.

    Here is the Gourmet Sleuth Converter.

    Here is the link to the recipe for my breakfast bread