Sourdough feeding calculator

How to best feed sourdough starter

Last update: 27.01.2022 – Changelog.txt

When you decide to create and maintain natural yeast (or mother yeast) you need to explore the topic of how to feed the sourdough starter. A sourdough feeding calculator is one of the most useful tool in your sourdough maintenance arsenal. In fact very soon you will want to know about:

  • feeding sourdough starter ratio
  • create store and backup sourdough starter
  • how much sourdough to use in your recipe
  • calculate ingredients to change the amount of sourdough starter at your disposal
On this page I will start concentrating specifically on the last bullet point. In fact, everything else is at the end of the day requiring to calculate how much flour and water you need for sourdough feeding. In order to make easy this apparently complicated process I prepared the sourdough feeding calculator. It will help you as a guide in your sourdough maintenance and recipes journey. So let me share it immediately for you to bookmark this page and use it every time you need. After I will explain a bit more in detail how to use the feeding calculator specifically in regards to the concepts of sourdough feeding ratio and hydration.

Sourdough Feeding ingredients calculator

If you have doubts using the calculator it makes sense to read the following. I will be sharing how to use the calculator and what you want to use as “options“.

What we want to achieve is to prepare ingredients to have the right sourdough starter amount to be stored or to be at the same time used as yeast (or levain if you prefer). In fact, when you use stiff sourdough in a recipe, it does not mean you want to remain without it for the next recipe. So it is incredibly important that when you feed your sourdough you create enough to keep some of it stored while using some of it as levain. Actually I just explained to you the “store and backup sourdough starter” concept I mentioned in one of the bullet points above.
The sourdough calculator then offers you two different scenarios:
  • calculate the ingredients for sourdough feeding (calculate feeding only)
  • calculate ingredients to create enough sourdough for feeding and storing (Calculate sourdough feeding for recipe)
In both scenario you need to fill the form options.  The most important ones are – of course – the amount of sourdough you need (either for storing and/or for a recipe), the hydration percentage and feeding ratio. Let’s focus especially on the last two options.

     Hydration of Sourdough

When we talk about Italian style stiff sourdough,  we normally expect hydration values between 40% and 50%. Nevertheless the sourdough feeding calculator offers the option to work with up to 100% hydration. In that way you can use it also for feeding the liquid sourdough ( in Italian). On the Internet you will find it mainly mentioned as “sourdough“, without any adjective. But in Italy we make a distinction.
In my recipes I normally use stiff sourdough with hydration between 44% and 47%. On the contrary I store my lievito madre normally at 44%.
I generally change the hydration only when I feed the sourdough for a recipe. If I am feeding only for storing it I never change hydration. Of course, this is how I manage my natural yeast and how I feel comfortable with it.

     Sourdough Feeding Ratio

The feeding ratio is particularly important. The calculator offers three different options:
  • 1:1
  • 1:1.5
  • 1:2
  • 1:3

First of all, what do we mean by this? Well, this option becomes relevant when you are doing feeding and maintenance of sourdough. In fact you can decide how much of the existing sourdough you want to re-use for the feeding and in what proportions you want to add the new flour. The new flour (with the water) will provide new food to the already existing bacteria population. When we use a ratio of 1:1 we mean that we use the same amount of existing sourdough and new flour. For a 1:2 ratio we use two times the amount of new flour on the existing sourdough.

For example, if we want to feed 50 grams of existing sourdough with a 1:2 ratio, we expect to add 100 grams of flour during the feeding process.

I use a 1:1 ratio only when I am feeding the sourdough several consecutive times for a specific recipe, for example to prepare panettone. When I want to feed sourdough with the sole purpose of storing it I use the feeding ratio of 1:2. Last, I use the 1:3 ratio if I need to store the sourdough for a longer period of time, for example if I am going to be for a few days on holidays. In theory it is safe to feed sourdough with proportions up to 1:6.