I am looking for an efficient formula to calculate the following.
Let’s say my starter is 60% hydrated and I want to do a single build to bring it to 100% hydration totaling 100g using a 2 parts flour to 1 part starter. I would like the formula to return the amounts of starter, water, and flour needed.
My brain is not handling this :-)
Ultimately, I plan to add this formula to my spreadsheet using specific cells to enter the variables. The variables will be original starter hydration, final build hydration, ratio of starter(total) to additional flour, and number of builds.
I appreciate your help.
Dan
So you have a starter that's 60% hydration
16g =6g water + 10g flour
Forget the 100g starter for a minute and let's see the ratio needed to bring it to 100% hydration with 1 part starter fed 2 parts flour or 1:?:2
16g starter + ? + 32g flour.
Well we have in total 42g flour and 6g water so we will need an extra 36g water. Now we know what "?" is.
16g starter + 36g water + 32g flour or 1:2.25:2
1+2.25+2=5.25
100/5.25 = 19.0476
So 19.0476g starter + 42.8571g water + 38.0952g flour
Obviously you'll need to round to the nearest whole number but that's the maths for you.
I am in the process of mentally disgesting this. If you are familiar with Excel, would you mine working this up for me?
If this is too time consuming, no problem. Given time, Im sure I can figure this out with the help youve given me.
Thanks
Danny
And you know that i'd help you anyway I can. However while I can do the maths, given time and a calculator, spreadsheets are beyond me. The logical side to maths I'm good at (to a point) but that's it. Throw a maths question at me and I'd work the answer out but ask me to do any sort of computer formula/programming I'm afraid I'd be of no use. So by all means I'd help the best way I can but I'm no computer expert.
Let me cite an example:
Say you have 50g of of the mother at 60% hydration and you wish to have 150g of starter at 100% hydration. Since you want 150g at 100% hydration, you will need half your starter to be flour and half water. Thus, 75g flour and 75g water.
Your initial mother is, via baker's math, 100% + 60%, or 160% of the flour amount.
50̣÷1.6=31.25g, 75g−31.25=43.75g additional flour needed.
31.25×0.6=18.75g, 75g−18.75=56.25g additional water needed.
∴ flour 31.25+43.75=75g, water 18.75+56.25=75g, or 150g at 100% hydration.
You can also simply add the computed weight of flour, then add water 'til the the final weight totals 150g.
gary
edit: While I was punching buttons to verify my math, Abe jumped in. We each used the same method with different starting values, so that may make it easier to realize a clearer understanding. Like Abe, I am Excel illiterate. Databases, not as much, but getting there. ~g
Abe is spot on.
I did this in a very similar way.
60% hydration starter = 160g.
1 part starter = 160g. 2 part flour = 320g.
Total flour thus far equals 100g + 320g = 420g.
100% hydration requires 420g of water. We already have 60g water. 420 - 60 =360.
So..
160g starter + 320g flour + 360g water = 840g
desired mass = 100g. 840/100 = 8.4.
Therefore divide all three parts by 8.4 =
19.05 starter + 38.10 flour + 42.86 water = 100.01g 100% hydration starter.
I can do an excel formula for you but I need more context.
Describe all your input cells and all or one answer cell(s)..?
Thanks Michael, I am looking at an Excel sheet with formulas now. I think it will have what I need. But if it needs tweaking or is not what I need, I’ll be sure to get back with you. Thanks for such a generous offer!
Once the sheet works as described and with permission from the owner(s) I hope to post it in downloadable form to be used by anyone interested.
Dan
Dan,
I created a bread calculator a while ago, and I use it for my own bakes. It is quite a bit more than what you have asked for, but it does incorporate the function within the spreadsheet. I have made it sharable in Google Sheets. I am working on protecting the sheet so someone can't inadvertently change something critical, but for now, if anyone wants to use it you can find it here. Please download a copy to your computer and use it locally rather than on the web page so it doesn't get corrupted. The instructions are listed on the introduction page, but basically, any cell that is yellow is user input and all the white cells are calculated. It is not as clean as BreadStorm or another commercial product, but it works for most bakes for me. Let me know if this helps.
-Brad
Many thanks to everyone that offered help. Alan, aka alfanso sent his sheet to me and it was a perfect fit.
If anyone is interested in the Starter to Levain Calculator, let me know and I’ll setup a download link. Alan gave me permission share his sheet.
Dan
this is why I keep my starter at 100%. I can’t do the math. Thank God for Abe’s formula - the only one I understood!
.6S flour and .4S Water = S. 2S becomes the added flour since it is twice the levain Call W the additional water required to make 100% hydration at the end. Z is the total levain weight. The formula becomes.
S+ 2S + W = Z total levain which isn't very useful until you know some other stuff
We know the flour and water have to be equal weights in the end for 100% hydration so each equals half of Z or .5 Z the only thing you have to know is the total levain amount in order to solve the rest.
so the flour is .6S +2 S = .5Z or 2.6S = 50. If the total amount of levain is 100 g then S becomes 50/2.6 = 19.23 g
The total levain is S so it is 19.23 g We know the added flour is 2S, so the added flour is 38.46g and the total water is the water in the levain plus the added water or
.4S +W = 50
So the added water is .4(19.23)+W = 50 or W = 50 - 7.692 or 42.31 g
You can check 19.23 + 38.46 + 42.31= 100 g .....who knew? The key to the math is knowing that the starter is made up of two parts of the total .6 and .4 of the starter total = S
The Excel should be fairly easy once the math is known and there are many ways to get the math right as we can see above.
A really cool spreadsheet would have you specify the hydration of your existing starter, the hydration you want your final levain to be and the total amount of levain you want. Say you have a 55% hydration starter and want an 82% hydration leavin and you want the total levain to be 825 g and you want to do 3 stage levain. Enter those 4 numbers and poof it tells you how much flour and water to add at each of the 3 stages. Should be easy enough. If you don't want to double the amount of flour and water for each feeding then it becomes more difficult and the Rule of 7 and 15 doesn't apply.
At least the brain still works a little bit.
"...the starter is made up of two parts of the total .6 and .4 of the starter total = S"
Bakers percentages would make that 66.6%