# Batch sizes and moulds

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#### PerthMobility

##### Well-Known Member
Our first batch consisted of 1,000grms of oils and we finished up with 1,250grms of soap from the mould or an increase of 25%. Is this about standard for CP and can I use that in order to compute the correct batch size for a given mould.

eg: A flexible 12 bar mould has room for 12 x 130g bars or 1,560g total soap weight/mass. So if I make a batch of oils to 1,560g minus 25% = 1,170g should I be just about correct with very little wastage?

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#### PerthMobility

##### Well-Known Member
Thanks PJ. Still furiously scratching head. I will apply T&E (trial and error) until I get it right. At least I have a bench mark to start from.

#### dibbles

##### Supporting Member
Supporting Member
To figure out your weight of oils for a particular mold:

L x W x H = Total Volume of the mold
Total Volume x .4 = oil weight needed for the batch

I have a mold that is 9" long x 3.5" wide x 2.5" high, so

9 x 3.5 x 2.5 = 78.75 then 78.75 x .4 = 31.5 (total amount of oils needed for a batch for this mold)

She uses the total volume multiplier of .39 rather than .4 - either will work

#### PerthMobility

##### Well-Known Member
Yes it does many thanks.

#### Steve85569

Supporting Member

NOTE that the .40 or .39 in NOT for the metric system. If you dig into the above thread some the correct constant for metrics is included. If I remember correctly it is .7? but I can't bring to mind the correct number.

Steve

#### KristaY

##### Supporting Member
Once you get it all figured out, write it down somewhere. I have many molds in various shapes & sizes. Some I use routinely so I just know what my batch weight should be. Others I only use a few times a year so I NEVER remember what the size should be. So pick either oil weight or total batch weight, whatever works best for you, and put it up or file it where the info will be most handy to you. I have mine written on a large post-it note and stuck to one of my shelves at eye level (along with several dozen other sticky notes) so I never have to go back to a previous recipe to figure it out. In fact, I just added large and small Pringles cans to list. That math was a serious chore for me.

#### topofmurrayhill

NOTE that the .40 or .39 in NOT for the metric system. If you dig into the above thread some the correct constant for metrics is included. If I remember correctly it is .7? but I can't bring to mind the correct number.

Steve
If my pre-coffee calculation is right, cubic cm * .69 is grams of oil.

#### Guspuppy

##### Well-Known Member
In fact, I just added large and small Pringles cans to list. That math was a serious chore for me.
What did you get for the large pringles can? I've gone through the mold thread and done so much math, getting a different answer every time, I don't know how to even guess! Haha

ETA: I've taken to writing the oil amounts on my molds in permanent marker. No need to guess which box I am talking about in my written notes then.

#### KristaY

##### Supporting Member
For the large Pringles can I got 53.5 oz. My total batch weight was 27 oz and it filled the can up to almost 7". I did the long hand math 3.14 (pi) x radius x radius x height. I also found an online calculator that got the same answer as I did so, yay me. Because I only had a couple of inches more that I'd want to fill it, I'll probably keep my batch weight at 35-40 oz.

#### PerthMobility

##### Well-Known Member
wow did I start something and me working in metric? Just to chuck some more fuel on the fire I have a mould sheet with twelve spots for soap. Each mould is 7cm wide x 7cm long by 3.2cm deep.

So I have added the formula 7cm x 7cm x 3.2cm x 12mould = 1,882 cubic centimeters. I then multiply 1,882 x .7 and get 734grms of oils needed. In this case one gram is equal to one cubic centimeter.

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#### The Efficacious Gentleman

If you're measuring in metric, the multiplier is 0.7, not 0.4. 0.4 is for imperial

#### PerthMobility

##### Well-Known Member
Saved by the "Efficacious Gentleman" again. Thanks Craig I should have known that. I do now.

#### DeeAnna

##### Well-Known Member
"...In this case one gram is equal to one cubic centimeter...."

That's only true if you're talking about water. The density for typical soaping fats is less than 1 g/cm3.

Try it yourself -- measure out 250 g of oil and see how many cubic centimeters (cm3) of volume that is. You'll end up with decidedly more cm3 than the grams you weighed out.

But the 0.7 multiplier factors in the density differences, so you're good.