The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Two Excel Tools for Sourdough

JMonkey's picture

Two Excel Tools for Sourdough

Two new tools:
Sourdough Spreadsheet
Sourdough Rye Spreadsheet

Lately, I've been playing around with my sourdough quite a bit. In particular, I've started keeping a very small amount of starter in the fridge -- about 30 grams or so -- and then building the starter I need from just few grams of "mother" starter over several builds or stages.

Doing the math is a pain. Especially when you're not only mucking about with builds, but also playing around with how much pre-fermented flour you want to use: 20% vs 30% makes a difference in terms of flavor and length of rise.

And then, if you get really nuts, you can start playing around with the Detmold three-stage process for making hearty rye breads, a fairly complicated arrangement that drastically changes how much flour you add and the hydration of each stage.

I got tired of searching for scratch pads and pencils to do all the math required to figure out how much flour I needed and when. So I build these two spreadsheets.

The first is for plain sourdough. Floyd was kind enough to upload it for your downloading pleasure HERE.

If you're using volumetric measurements (cups), I'm afraid this won't be much use to you. There's already a ton of variation in the weight of one cup (In The Laurel's Kitchen Bread Book, for example, a cup is roughly 5.25 ounces! 3 cups = 1 pound!), and with sourdough starter, all bets are off due to all the pretty bubbles.

Any generic weight units will do, so long as they're all the same. Grams are easiest, because they're more precise. As such, I've set the default for most cells to round off to the nearest whole number. But if you'd like to change the defaults to enable decimals so you can use ounces, I'll be glad to show you how to do it.

A few points:

  • Fill in ALL the yellow shaded areas to get a result.
  • Make sure that the "Final Starter Hydration" matches the figure that you put in for the hydration of whatever the final build is.
  • Starter innoculation refers to the percentage of pre-fermented flour that you use. 20 to 30 percent is common.
  • Multiplication factor refers to the amount by which you want to increase the amount of FLOUR in each build. You need to increase it by at least 2. At room temperature, a factor of 8 will probably take 12-14 hours to mature. A factor of 4, about 6-7.
  • There's a box that lets you set how much starter you want to have left over. I did this so I could have fresh, refreshed starter to pop in the fridge if I wanted and also becuase I always seem to lose a bit along the way as it sticks to the bowls, utensils and fingers.

    The second spreadsheet is for rye breads, and it's almost exactly the same, except that it allows you to determine the percentage of rye you want in your bread. Download it HERE.

    I'm using this spreadsheet to build my first 70% Detmolder rye with whole wheat. Hee hee! I'll post the results next week. Saturday is baking day. Can't wait!

    Hope you enjoy these tools and find them useful!

  • breadnerd's picture

    I didn't have time to look at these super closely, but the idea is great!


    I too have my bread formulas in excel :)

    One time figuring out the baker's percentage formula, and now I just cut/paste it as needed. It's handy just to plug in the final dough weight and have the proportions all ready for you.




    - breadnerd

    commonloaf's picture

    Nice job on the excel chart.  I wondered if you knew how to make a chart where if you altered the hydration in a given recipe, excel could recalculate the flour needed per loaf so that the desired final weight would stay the same (920g for example)?  If you want I could send you a file that illustrates what I am talking about. Does this make any sense?

    Just Loafin's picture
    Just Loafin

    Not sure you'd want to use the flour content to alter dough hydration. Doing so would then alter the percentages/ratio of ALL the other ingredients! It's much better to alter the amount of water, unless changing the other ingredient ratios is desired...

    At any rate, let's use water as the example, assuming all you want to do is to change the hydration.

    Let's say you have 1500g of dough to build, which is going to include approx. 750g of flour and 474g of water. 474 divided by 750 = 0.632. We move the decimal over two places to the right and get a hydration of 63.2% (if you are using any type of poolish/starter, that needs to be factored into a final hydration percentage. It will raise it depending on the hydration percentage of the poolish/starter used. That's beyond the scope of this simple response).

    Ok, so we have 750g flour, 474g water and that worked out to 63.2% hydration. Let's bump that up to 65%. 750g times .65 = 487.5g, so we would need to raise our amount of water from 474g to 487.5g. To check our math, let's do 487.5 divided by 750 and we get exactly 0.65 or 65%.

    We have now raised the hydration of the dough without altering the other ingredient's relationship to the 100% flour. You can use the exact same math formula to alter the flour weight against the water, but to keep the entire recipe formula intact, you would then need to re-calculate all the other ingredient weights. That's a lot more work. Hope that helps!

    - Keith

    davidg618's picture


    I've built some similar Excel spreadsheets. The SD Starter Calculator works on a similar premise: It calculates the seed starter (your term: mother), and the flour and water quantities for a three-build approach given a target starter quantity, and a target starter hydration. The fundemental approach is to increase the seed starter's or intermediate build's mass 3x each build, and increase or decrease the seed starter's hydration by 1/3 each build. Thus Build-three yields the target starter mass (27x the seed starter mass), at the target starter hydration. Like you, I built them to avoid the PTA math each time I want to bake.

    The second spread sheet (two versions: oz. to gms, gms to oz.) helps me formulate my own bread formulae, or convert straight dough recipes to SD, poolish, or sponge formula. It does a lot of the routine math to make it easier, but still gives the user control on what flours and how much of each to use, the final dough quantity and hydration, starter quantity and hydration, calculates salt needed with a 2%, and provides for flavor additions, e.g., fruit, nuts, cheese.

    If you're interested they are available on my wife's web site ( I don't have one) at:

    David G.

    photojess's picture

    I just downloaded your starter and bread sheets..  How would one know what the target weight is going to be?

    Thanks by the way.  Hopefully, I'll get or need to use them~  but thanks for doing the work

    davidg618's picture


    How much bread do you want to make?

    Let's take an example: Suppose you want to make 4 500g loaves (that's 1.1 lbs). total dough weight would be 2000g. But dough loses about 20% of its weight during baking, so if you want your finished loaves to weigh 500g, add 20% of 2000g (=400g). So your target dough weight would be 2400g.

    David G

    photojess's picture

    um....I didnt' know a ~lb loaf weighed 500 gms.  So now I know!  There are so many basic stuffs that I seem to keep finding out I don't know!

    And this metric stuff is hard getting used to.  I was always a volumetric person.  "Seeing" what 10 or 50 or 100gms looks like is a learning process too.

    Larry Clark's picture
    Larry Clark

    are outstanding and I'm sure I'll use them often. Adding eggs as an ingredient to the bread formula would be a big plus.



    davidg618's picture


    Under "Fluids" there are three blank cells for things like eggs, orange juice, heavy cream, etc. just enter their name and weight, and the weight will be taken into account in the hydration and total dough weight calculation.

    David G

    cake diva's picture
    cake diva

    I use David G's spreadsheets.  Works great!

    Andreas's picture

    That's fantastic. I've been working on developing a "feel" for my bread, including the starter - meaning I am judging activity levels and how much to add by eye and nose. So far this has been working really well, but getting it down to a formula is probably something I really should be working towards. 

    Thank you so much for sharing this. 

    twcinnh's picture

    The page with the spreadsheets seems to be gone.  Has anyone these sheets they could re-upload somewhere?


    Tom C

    Just Loafin's picture
    Just Loafin

    As mentioned below, both links seem to be working... if you're still having issues, post back, and I can upload them to my server for you.

    - Keith


    isand66's picture

    Download it from the top links and it should work.  I was able to do it.

    twcinnh's picture

    Sheesh.  I got lost in the narrative.  Hence, the head banging on the right.


    Tom C

    clazar123's picture

    The link that doesn't work is from davidg618-it used to be posted on his wife's site but that was a few years ago, now.

    "Page Not Found" link:

    Thank you!