The Fresh Loaf

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Converting a recipe that uses Instant yeast to a sourdough starter recipe

BrotBoy's picture

Converting a recipe that uses Instant yeast to a sourdough starter recipe

Can anyone tell me... Is there a simple approach to convert  a recipe that uses commerical yeast to a sourdough starter , I have been very happy with the sourdough starter that i am using  and now want to convert more recipes to this style of bread making,

  Looking forward to some ideas



SourdoLady's picture

This is my favorite way to convert to sourdough. It is by no means the only way to do it, but I like it because it is a very simple method......

Converting to Sourdough
The easiest way I have found to adapt a recipe without altering the ingredients too much is to take all of the liquid from the recipe, stir in 2 Tbsp. starter, add the same amount of flour as the liquid. Let this sit, covered, overnight (room temp.) Next day, continue by adding the rest of the ingredients, remembering that you already used the liquid and part of the flour. If your recipe calls for milk rather than water, use water but then stir in some dry milk powder after the overnight proofing is complete and then mix your dough.

sallam's picture

I like your method so much. I know its a 4 year old post, but do you still use that sourdough poolish method?

Do you use 2T of starter whether you're making a large dough or a small one?
And regarding the first bulk proofing, how many hours does it take for it to double in size? and do you do a second proof? if so, for how long?

SourdoLady's picture

Yes, I still use and like this method. When you say 'large dough' I'm not sure how large  you mean. Most of the time when I bake I make a recipe that yields two loaves. If your recipe is larger than that, you may want to up the quantity of sourdough you start with, but you don't have to. Less starter means longer fermentation time and also will yield more flavor--especially more sourness.

The proofing times will vary a lot. It depends on the vitality of your starter, dough temperature and room temperature. Also, more starter means a quicker rise, but less flavor in the bread. Whole grains, especially rye, will ferment and rise faster. Lean doughs usually rise quicker than enriched doughs (those with fats, sugars, eggs, etc.).  Yes, I usually do a second proof. I didn't when I first started baking with sourdough, but I do now because I think the bread turns out much better--texture and flavor.

Valdus's picture

This is seriously whoa! I’m going to use this on every recipe in FWSY.  

David R's picture
David R

I mean, sure, you could... but why would you?

It's like finding a post on how to convert any tricycle into a bicycle by cutting off both of the rear wheels and then reattaching one of them in a centred position. If you had a tricycle that you really loved, it was the only thing you were ever able get a comfortable ride out of, but you won't be able to ride it anymore unless you get rid of one wheel, then I guess you convert it. But going around converting all the tricycles you can find, just because you discovered a usable method? Normally, when you want a bicycle, you look for a bicycle from the start. And normally, when you want sourdough bread, you use a sourdough bread recipe. IMO, converting from a yeast recipe is mostly for when no one has ever made a sourdough version of what you want - or they have, but all the existing recipes turn out terrible. And it's not like there's some terrible lack of actual recipes for sourdough bread. ?

I know, I know, I keep on about this... Maybe I should approach it from the other direction, and ask why people even bother to glance at recipes in the first place, when they could just improvise the entire process from start to finish, using no guide whatsoever.


Edited to add: I intend no disrespect to any of the methods or their authors. I expect that they work pretty well. I'm not questioning their usefulness or their existence, just their potential (mis)use as a primary everyday method of baking.

jkandell's picture

Make 1 cup of sourdough starter by your usual methods, ready for the morning. Use either 100% hydration or 50% hydration so you know how much water and flour you used.

Add remainder of flour and water and other ingredients (leaving out any oil)


FMM's picture

I have a question on the same theme.  If a recipe calls for both a starter and commercial yeast, if I am willing to let the dough ferment much longer than the recipe calls for, can I just skip the added yeast and if so, do I make any adjustments to the amount of starter called for in the recipe?  I'm thinking of many of the recipes in Dan Lepards book which use fresh yeast in addition to levean.  I prefer to avoid adding yeast if I can.


SourdoLady's picture

Yes, you can do it with no other adjustments. Just omit the yeast and mix the recipe as usual but your proofing times will be much longer without commercial yeast.

cake diva's picture
cake diva

 4 cups bread flour
1 cup warm water (105° to 115°F)
1/4 cup honey
3 tablespoons canola oil
1 1/4 teaspoons salt
1 egg, lightly beaten
1 package dry yeast (1/4-ounce)

 I have a 1/4/3 (by volume) starter ready to substitute.

ryeaskrye's picture

I can't remember where I read this in the past, but you can typically replace the yeast with 1/4 to 1/2 cup of starter and simply subtract out the appropriate amounts of flour and water from the recipe. I have had good results this using this method and tend to use the 1/2 cup.

However, I believe it depends a little on the hydration and active state of your starter. Using your 1/4/3 ratio by volume , it is difficult to tell what your hydration is. If you mean 4 parts flour per 3 parts water and assuming 1 cup of flour weighs around 125g and 1 cup of water weighs the standard 236.6g you have a fairly liquid starter at 142%.

Given an accurate "cup", the water weight will be close, but the problem is that the weight of a cup of flour will vary wildly from person-to-person and flour-to-flour. That is why most recipes you find posted here at TFL list ingredients by weight. A scale is one of the best tools to help build consistency in bread baking.

My starters are kept in a high hydration, liquid state and generally weigh in around 250g per cup. I build an "inoculated" starter for a bake and bring it to 100% hydration in the process, which is not as difficult as it sounds. I normally substitute around 120-140g.

If a starter is kept active at 100% hydration (fed with equal weights of flour and water), I substitute 140g of starter for a packet of yeast and subtract 70g from both the water and flour components of the recipe.

cake diva's picture
cake diva

Yes, by 1/4/3, I meant 1 part starter, 4parts flour, 3 parts water- all by volume.  I do agree to 1/3/4 if that is what convention dictates.  With your clarification above, I'll be able to do the conversion. 

I wish I had joined this community before I bought my scale!  Looks like I'll have to buy a digital good to at least 1gram.

ryeaskrye's picture

Don't forget that your rise times will increase substantially. I don't feel accomplished enough to tell you how to predict exactly by how much. I guess for the most part and keep an eye on the dough.

For my most recent conversion, the bulk ferment rise time went from 2 hours in the yeasted recipe versus 5 hours in the sourdough. The final proof stayed around 1.5 hours in both.


Chuck's picture

Usually digital scale resolution (1 gram, 1/10 gram, etc.) is related to maximum capacity (5kg, 0.1kg, etc.) A scale that has enough capaciy (i.e. is "big enough") to handle your mixing bowl, flour, etc. almost certainly won't also have the fine resolution you need to measure yeast and salt. So what to do?

Possible solution 1: Get a scale with 1 gram resolution and large capacity for your mixing bowl, flour, and so forth. Then use measuring spoons for the small ingredients like yeast.

 pro: it's easy, it's cheap

 con: you still have some "volume" measures (the measuring spoons), you may need a calculator to use baker's percentage recipes

Possible solution 2: Get two scales - the large one as above and also a small one (for example: 1/10th gram resolution, 100 grams capacity)

 pro: you're weighing everything (no "volume" measures hiding anywhere), no need to own and wash a lot of measuring spoons, no weird calculations

 con: buying two scales costs more

LeadDog's picture

Here is what I do to convert a yeast recipe to a sourdough recipe.  I use 20% to 40% sourdough when compared to the amount of flour that the recipe calls for.  Some people use 20% in the summer time when it is warmer and 40% in the winter time when it is cooler.  You can go back and forth between these numbers for a number of different reasons like fermentation times or flavors.  I use recipes that use baker's percentages and use the same percentages of hydration, salt and what ever else the recipe calls for.  Keeping the percentages the same as the original recipe and using 20% to 40% has worked well for me.  I also have a spreadsheet that I use so that I can use a starter with the hydration of my choice.  The spreadsheet is used to make sure I end up with the same hydration of the original recipe.

trailrunner's picture

you use somewhere between .4# and .8# of firm stater in th recipe ? I am trying to convert my Challah and it has 7 c unbl bread flour. I saw where on person used 2 Tbsp of starter in any bread recipe to convert to sourdough and left out the yeast. Your way would take considerably more. Just trying to clarify. Thank you

LeadDog's picture

Trailrunner yes that is right.  I currently am making bread that uses a starter at 25% of the weight of the flour.  The starter is at 50% hydration.  My spreadsheets are online at  The spreadsheet is geared to a final dough weight first then just put in the percenatages of your ingredients.  It is also more geared to working with grams but has pound and ounce figures on it too.

trailrunner's picture

Just what I needed to know. I am so pleased that you gave me the link to the spreadsheet. I am not computer literate but my husband is so I am sure to be able to utilize it. Will keep you posted as to how it goes. 

LeadDog's picture

Most of the time I try to find if someone has done a sourdough version of what I want to bake first.  It makes it a lot easier.  Here are a couple of links for sourdough challah.

shawnamargo's picture

I have a recipe for a pain de compagne that calls for yeast in two places of the recipe, a 1/2 tsp in thepoulishe and then an additional 1/2 tsp  for the dough portion of the recipe. How do I use my sourdough starter? Is it just used in the poulish part of the recipe?

Mini Oven's picture
Mini Oven

Feed 1/4 cup of your 100% hydration starter using the flour and water from the poolish (drop the yeast from the recipe) and let ferment overnight at room temperature 8 to 12 hours.  Remove a portion of this preferment to adjust weight if desired.  Then add the rest of the ingredients and continue. 


AnnaInNC's picture

starter equals 1 teaspoon of yeast ?    

Actually, I was just looking for the same but in reverse. I need to bake something for tonite but do not have enough active starter. 

Thanks, Mini


Chuck's picture

Be aware there's plenty of disagreement about the appropriateness of "converting" a recipe from commercial yeast to sourdough starter.

Many folks say it's in principle very easy  ...even though it's hard to give an exact measurement rule because starters are so variable. Here's one thread (there are many many others here, as well as lots and lots of discussions elsewhere on the web) that talks about converting a recipe to use sourdough starter.

On the other hand there's significant opinion that it's not really such a good idea. Here, from Susan's Wild Yeast Blog, is one of the better relatively detailed explications of why not.

(Or, as MiniO herself once said: "By the time all the changes have been made in flour, water and fermenting times to figure a sd starter, writing everything down, it might just be easier to go with a sd recipe.")


(I dimly remember a post titled something like "starter is not a drop-in", but now I can't locate it. Can somebody else help find it?)

pmccool's picture

Aim to have about 20% of a formula's flour (by weight) contributed by the starter.  No, that isn't a magical number.  If you look at sourdough bread formulae, you will notice that many of them have anywhere from 10% to 30% of the flour contributed in the starter/levain.  And there are outliers that go beyond that range, too.  The 20% number is easy to work with and should give you consistently good results.

Part of the reason you haven't found a conversion table is because there are so many different ways to skin this particular cat (see numbers mentioned above) and they all work.  Starters are notoriously idiosyncratic.  That's true of my starter compared to your starter.  It's also true if we just look at the behavior of our own starter from one day to the next.  Not to mention whether we take it at its peak, or somewhat before, or somewhat after.  What you want to do with your starter is bring a sufficient supply of yeasts to the party (your dough) so that your dough inflates as desired.  The density of yeasts in anyone's starter is highly variable, so how to build a table that covers all of the possible variations?  Hence my suggestion to use "about 20%", rather than "exactly 20%" of the formula's flour in the starter.  I can't even call it a rule of thumb.  It just seems to work fairly well, probably because it delivers a sufficient number of yeasts to raise the dough in a reasonable amount of time.


pmccool's picture

And I'm glad you found it helpful.



Peggy Nielsen's picture
Peggy Nielsen

Hope you're still around! Trying to transfer yeast to sourdough in Rugbrod.  Question is do you add rye berries, flax seed,  etc to flour weight?