# How to calculate how many pounds my cold process soap batch will be



## Loni S (Dec 29, 2020)

I'm confused about what is used to determine how many "pounds" of soap my batch makes (and I haven't had any luck searching online and on this forum). Do I add up the weight of all of the ingredients that goes into it, including the lye, water and essential oils?  Is it a different weight after the lye has done its chemical reaction? Or do I literally just weigh it after it's made and has cured so all the evaporation has happened?  I'd love to know what the standard is for measuring this so I have a frame of reference when I'm reading other's recipes, etc.

Thanks so much!


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## lsg (Dec 29, 2020)

Here is a link with some info.:  How to figure how much oil for mold.


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## KimW (Dec 29, 2020)

Just FYI - that is a great link.  Be sure to read through the whole thread as you're able.  

The formula given is a good one, though it is for using a certain amount of water.  That is, it's for using about a 33% lye concentration, or about a 2:1 water:lye ratio.  That said, it is still a good starting point.


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## DeeAnna (Dec 29, 2020)

Loni S said:


> I'm confused about what is used to determine how many "pounds" of soap my batch makes.... Do I add up the weight of all of the ingredients that goes into it...



I'll take a stab at answering the question I think you're asking -- 

When soap makers talk about a batch of soap or the ingredients in the soap, they often use the weight of the fats as the standard of comparison, not the total weight of the entire soap batch. They'll usually say something like "the batch is made with 42 ounces of fat". They are much less likely to say "the batch weighs 64 ounces total."

Why? The total weight of fat is the largest ingredient in soap. It is also the one ingredient in soap that remains a constant. For every pound or kilogram of fat, soap makers will use more water or less, more scent or less, no or some or a lot of additives, and so on. Even the lye (NaOH) weight can vary depending on the soap maker's choice of the superfat percentage.

All these choices means the total batch weight can vary quite a bit. That makes it hard to use total batch weight to compare batches of your own soap or compare your soap with another person's soap. A more consistent way to make these comparisons is to use the total fat weight. It's not perfect, but it's better than the other options.

Bakers do the same thing -- they will use the total weight of flour as their basis, not the total weight of the bread dough or cake batter. Look up "baker's percentage" for more info.

FWIW, I wrote an article that gives step by step instructions and the math background for the "0.40 Rule" and its metric equivalent. These are ways of estimating how much soap batter a particular mold will hold. The answer you get is the ounces or grams of fat needed for the batch, not the total batch weight. See -- Estimate batter to fill a mold | Soapy Stuff


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## Loni S (Dec 31, 2020)

Thanks all.  I'm getting the impression that there's no cut-and-dry rule   More experimenting then!


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## earlene (Jan 1, 2021)

I like Marie Gale's articles on Determining net weight of soap.  It is for labeling purposes, but it is applicable to determining the net weight for your entire batch as well.  She gives two different methods in:









						Calculating the Net Weight of Soap (Part 1)
					

When you are labeling soap, one of the problems is figuring the net weight to put on the label. Since water will continue to evaporate out of the soap making over time it will gradually weigh less, even after the initial “cure time”. The net weight stated on the label may NOT be more than the […]




					www.mariegale.com
				











						Calculating the Net Weight of Soap (Part 2)
					

In part 2 of this series, we calculate the lowest net weight a soap bar could be over time, if all the water evaporated out.




					www.mariegale.com


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## Zany_in_CO (Jan 2, 2021)

Loni S said:


> I'd love to know what the standard is for measuring this so I have a frame of reference when I'm reading other's recipes, etc.





Loni S said:


> I'm getting the impression that there's no cut-and-dry rule   More experimenting then!


To find the weight of your soap batch, this formula has served me well since I started soaping in 2004 :

Weight of oils X a factor of *1.37* = weight of soap (approx.)

Example:
32 oz. oils X 1.37 = 48 oz. soap (approx.)


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## TheGecko (Jan 2, 2021)

Loni S said:


> I'm confused about what is used to determine how many "pounds" of soap my batch makes (and I haven't had any luck searching online and on this forum). Do I add up the weight of all of the ingredients that goes into it, including the lye, water and essential oils?  Is it a different weight after the lye has done its chemical reaction? Or do I literally just weigh it after it's made and has cured so all the evaporation has happened?  I'd love to know what the standard is for measuring this so I have a frame of reference when I'm reading other's recipes, etc.



As noted by @DeeAnna, most soap makers define the measure of their soap by weight (ounces or grams) of oils/butters because of all the other variables...Lye Concentration, SuperFat, E/FOs, and additives which can affect the 'batch' weight. Those same variables, along with time, can affect the 'cure' weight. So I guess the 'standard' is _*Weight of Oils*_.

Recipes generally come in two forms...percentages and actual weight (ounces or grams). If you have a recipe that has actual weight measurements, you would just add up all the ingredients (oils, butters, lye, water and E/FO) for a general 'batch' weight. It should be noted that alternative liquids...creams/milks, fruit/vegetables purees are part of the 'batch' weight. I say 'general' because there are dry and dispersed additives that can add to the weight and/or volume depending on how much is used. And while we generally don't use volume as a measurement, consider a pound of gold vs a pound of feathers...a pound is a pound, but by volume, there is a HUGE difference. So while a half ounce of say Calendula Flowers doesn't sound like a lot of weight, by volume it could mean that you need a bigger boat (or mold).

If the recipe comes in percentages...'batch' weight is moot for reference as it is dependent on what you want to make.  I prefer percentages since those who provide them usually provide Lye Concentration, SuperFat and additives PPO.


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## Loni S (Jan 2, 2021)

Thank you so much everyone!


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