The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Anyone can help me understand Baker’s math?

donnnaaai's picture

Anyone can help me understand Baker’s math?

Help me please, I read many blog posts about Baker’s percentages but my dumb ass still don’t understand. I want to convert the percentage to grams or write my own recipes or convert any yeast recipes to sourdough. An easier explanation please. I’m terrible at Maths

BaniJP's picture

In baker's math the amount of flour is always 100% or 1 part. Any other ingredient amount is calculated based off that, for example:

If your recipe calls for let's say 500 g flour, 350 g water, 10 g salt and 5 g yeast, the baker's percentages/math would be:

100% flour                               = 500 g
70% water (350/500 = 0,7)      = 350 g
2% salt (10/500 = 0,02)           = 10 g
1% yeast (5/500 = 0,01)          = 5 g

This way you can easily multiply a bread recipe and calculate other ingredients amounts when you know the amount of flour (the most important ingredient). Say if you have 10 kg of flour, you immediately know you need 7 kg water, 200 g salt and 100 g yeast (based on formula above).
The whole point of baker's math is just to calculate faster. If I write a recipe, I usually write it in baker's math and the grams in brackets.

In other recipes where flour is not the main ingredient or present at all, for example puddings, mousses, cremes etc., usually the ingredient with the biggest amount is taken as the 100%/1 part calculating base.


For converting a yeast recipe into a sourdough recipe, usually you replace 1 package of dry yeast (11 g) with 1 cup mature starter. Of course you need to change the amount of other ingredients a little since with the starter you are introducing additional water and flour.

Hope this helps! I'm sorry to say that baking always involves math as soon as you deviate from the original recipe, even if it's just doubling it.

foodslut's picture

Just one question -- I bake by weight, so how much would a cup of mature starter weigh for a conversion?

Angelica Nelson's picture
Angelica Nelson

Most people will note the weight of the starter s a percentage of flour, then note the hydration level so it might be 20% starter at 70% hydration.

Hydration is the total flour in grams divided by the total liquids in grams. 

JeremyCherfas's picture

After an excellent explanation of how to use baker's math, I found it funny that the yeast replacement was couched in terms of cups of starter. To stay with useful amounts, I usually think in terms of the amount of the final flour that will be prefermented in the starter.

Of course this gets us deeper into the weeds, as another person commented, but it does at least have the virtue of consistency. And for what it is worth, I generally aim for somewhere between 20% and 40% of the total flour weight being in the leaven.

alfanso's picture

In agreement w/Angelica and Jeremy

Both the esteemed Mr. Jeffrey Hamelman and the BBGA (Bread Baker's Guild of America) refer to the levain (sourdough) amount in terms of a percentage of the pre-fermented flour.  And I'm certain they are not the isolated cases in belief of that.

To give you a representative image of what that looks like on a spreadsheet in its "simplest format",this is a BBGA abiding example:

Pain au Levain        
Jeffrey Hamelman        
     Total Flour    
 Total Dough Weight (g) 1000 Prefermented15.50%   
 Total Formula   Levain  Final Dough 
 Ingredients%Grams %Grams IngredientsGrams
 Total Flour100.00%599.5 100.00%92.9 Final Flour506.6
 Bread Flour95.00%569.5 93.5%86.9 Bread Flour482.7
 Rye5.00%30.0 6.50%6.0 Rye23.9
 Water65.00%389.7 60%55.8 Water333.9
 Salt1.80%10.8    Salt10.8
 Starter3.10%18.6 20%18.6   
 Totals166.80%1000.0 180%167.3  1000.0
donnnaaai's picture

Thank you all responses! Unfortunately I’m so stupid I still can’t understand 

Mini Oven's picture
Mini Oven

than you give yourself credit.   Following good recipes can help you in tweaking recipes to your liking.  You can certainly bake great bread and use recipes without having to use bakers math.  A tiny bit of normal math helps if you want to double or reduce a recipe for more or single loaves.

Just keep track of what you put together including the specific names of the ingredients and their weights.  When you need help, give a yell and mention the fact that math is a foreign language to you.  You certainly aren't the only one.  Even if you confuse numbers, you can take a photo of the ingredients on the scale and have a second person read the photo if needed. 

Bakers math is just one way of communicating a recipe.  Volume or cups is another.  

A simpler way to look at the percentages of bakers math recipes.... let's take this simple basic one:

100% flour.  Change to 1000 g flour by multiplying by ten grams.

70% water    Change to 700 g water by multiplying by ten grams.  (Oh, a 70% hydration dough!)

2% salt.       Change to 20 g  salt by multiplying by ten grams.

now if you add up the grams, you've got a dough that will weigh 1720g if you get every little tiny bit of dough off your fingers, bowl and spoon.  Is that enough dough or too much?  If you want less, half all the ingredients.  That would give you 500g flour, 350g water and 10g salt.  Look familiar?  Read thru it again. See?  You can work it like that or ( big "or") instead of multiplying a percentage by ten grams and halving it,  multiply the percent in the recipe by five grams.

Does this help?

There are about six different ways to teach and solve math problems and most countries teach only one abstract way or maybe two methods if you are lucky.  We are not all born with the same brains and I wish schools systems would recognize and use a variety of methods to teach and solve math problems.  What about those who see math numbers turned around, flowing or distorted or found a better way to work maths or just so frustrated by math they choose to avoid it?          >stepping down from my soap box<


Angelica Nelson's picture
Angelica Nelson

There are a lot of recipes that don't require it, but if you want to use baker's percentage, then you start with the flour. 

The purpose of baker's percentage is to reduce or eliminate variation from baked goods. A non-BP recipe may not turn out the same way each time.

The total flour is always 100%.  All other percents are comparisons to this amount.  So you *define* the amount of flour as 100%.  There is no conversion or calculation for the flour.  The idea is to write a recipe in such a way that I can make 1 loaf of bread or 100 loaves of bread, and they all turn out the same. And it tells me how much of all the ingredients I have to keep on hand to make the batch of bread I am planning.

Then you compare all the other components to the number of grams of flour. 

If 500g = 100% for the formula you're using today, then.... probably you're making only one loaf today. 

Then if the recipe calls for 2% salt, you multiply 500g by 0.02, and that tells you how many grams of salt you need.  In this case you would need 10g of salt for 2%.

Do the same with the other ingredients. 


It gets harder if you're making a multigrain bread. 

Total flour in grams = 100% by definition.  Let's say you're planning 1000g for roughly two loaves.

So if you're using a recipe with 30% rye flour, then it looks like this:

70%  bread flour = 700g

30% rye flour = 300g

.... then the other ingredients...

2% salt = 20g

This method is the one you need for gluten free baking.  Opinions vary whether gluten replacement ingredients like flax seed or psyllium is a "flour" or not.  As long as you're being careful to do it the same way each time, the recipe should be repeatable.  The goal is to keep notes so you can repeat the recipe and have it turn out the same.


If you're developing a recipe, then it's important to measure everything you add and keep notes on how you're handling all the ingredients.  Usually you're calculating up all the grams of flour you used and then later working out the percentage, you can't really be sure your recipe will turn out the same on every baking occasion in the future.  Even with BP a lot of small variations can affect the outcome.  Even just switching brands of flour.



foodforthought's picture

Sone TFL discussions can get deep into the weeds. But you don’t have to go there until your ready and willing, if ever. Understanding that Baker’s Math is just a way of comparing all dough ingredients to the total amount of flour in a recipe is really all you need to know. Knowing what it is and how to apply it may be two different things, though. IN any event, you shouldn’t have to actually use the math much unless you’re trying to scale a recipe up or down.

To stay sane I have a simple rule: maintain starters, levains and poolishes, if using them, at 100% hydration. This way I know that 50 g of starter contains 25 g each of flour and water. The levain I make from the starter is also maintained at 100%, so let’s say I add 100 g each flour and water to that 50 g of starter. Now I have 250 g levain that contains 125 g each flour and water.  

If I want to use all 250 g of levain in a recipe calling for 500 g of flour and 350 g of water (a 70% hydration dough), I would mix the levain with 350-125 or 225 g of water. Then I would add 500-125 or 375 g of flour to the levain/water mix. 

Make sense?

Happy baking,


Mini Oven's picture
Mini Oven

if you have a scale...  first stir down the starter to pop bubbles and decrease the volume. Then put the cup on the scale and either reset the scale to zero or note the weight of the cup.  Then fill the cup with the stirred down starter.

How much does it weigh? 

If the cup weight is included in the weight subtract it to get the weight of the starter.

Angelica Nelson's picture
Angelica Nelson

Apparently there's a computer program for this:  Breadstorm? I have a hard time reading small type.  Looks like a lot of detail in there.