# 1lb soap = 2 cups? (Liquid)

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#### Nutty

##### Active Member
Okay so I haven't made anything yet, but I have a recipe to make a simple 1lb batch of soap. My question is...a 1lb batch of soap is the equivalent of 2 Liquid cups right? So if I wanted to test a mold with water, Can I just fill up 2 cups of water and pour? Or am I missing something? Basically I'm trying to be cheap and have a DIY soap mold for now but want to know that it will be big enough. :mrgreen:

#### Soapsavvy

##### Well-Known Member
Hi Nibbie, yes I think you get just under 2 cups of soap from 1 Lb which would be equivalent to 8.7 Ounces. Hope it helps, I'm a newbie too, but I've done a ton of reading!!

#### newbie

You can use a formula to figure out how many ounces of oils will fill that mold.

Measure length x width x height in inches and then multiply that number by 0.4 and that will be how many ounces of oils you need.

There is a stickie up at the top of this page about to calculate how much oil for a mold. It's always there to reference in case you lose this or forget what the calculation is.

#### DeeAnna

##### Well-Known Member
"...is...a 1lb batch of soap is the equivalent of 2 Liquid cups..."

If soap was pretty much mostly water, you would be pretty close to right. "A pint's a pound the world around."

But fat is a big part of soap and fat weighs less than water for the same volume. That means the actual volume of 1 pound of soap is going to be more than 2 cups. It's a better idea to follow Newbie's advice to get a more accurate answer.

"...just under 2 cups of soap from 1 Lb which would be equivalent to 8.7 Ounces..."

I'm not sure I'm following your train of thought -- can you explain, please?

#### newbie

Whoa there!

This a forum where people talk and ask questions and are polite and curious. Asking about a person's line of thinking is not uncommon here and is not automatically a challenge.

We're not very big on rudeness and comments to mind your own business when you've posted a response to a question.

#### Nutty

##### Active Member
Okay so I should just make 50 pounds of soap and hope for the best then. xD

#### newbie

I'm not sure what you mean, Nutty. No one is saying you should make a big batch of soap and in fact, most advice would be to start with one pound batches. However, soap is best made with weight measurement and not volume because volume is too inaccurate. That's why I suggested you measure your mold in inches and then calculate how much oil to use to fill that one pound mold. If your recipe is for 16 ounces of oils and the calculation tells you you need less for that mold, you can adjust it.

If you mold is bigger and you want just to make a one pound batch total, I would use a soap calculator to put in your recipe and then have it give you all the weights for your ingredients so that oils total 14-16 ounces. You'll have a little left over but you can then make an individual bar with it.

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#### DeeAnna

##### Well-Known Member

No, you didn't. But you shared your answer on a public forum so the information is freely available to forum members. All of us have the right to read what you share and if needed ask you for clarification. The private message system is the way to communicate if you don't want what you say to be open to questioning.

I'm asking for your help, because if I don't understand, that's what I do -- I'm going to ask. You and I got crosswise once before, but I would prefer to be on a more polite and kinder footing with you.

I really do want to know the process behind your answer, because I'm coming up with something that's quite different. If I'm wrong, I'd like to learn and do so in a spirit of kindness. I invite you to help me.

#### shunt2011

##### Moderator Emeritus
Moderator Emeritus
She asked you a very simple question in a polite way. Your extreme rudeness was totally uncalled for. This is a public forum. If you put something out there folks are certainly free to ask questions.

Please rethink your responses going forward. This kind of behavior is not tolerated on the forum.

#### Nutty

##### Active Member
I was just joking about the 50 pound batch. But thank you guys! That equation "Length x Width x Height x .40" is fantastic.

I also wanted to ask...and this has nothing to do with the original question, but is 30% lye/water concentration a standard? Even if I were to make that 50 pound batch (haha), would that 30% be okay? I'm just curious as to why 30% is used.

#### DeeAnna

##### Well-Known Member
Hi, Nutty -- Once you fix the type and weight of the oils and choose a lye discount (also known as superfat; 5% is common) -- then that fixes the amount of lye you need. Once the fat and lye weights are set in stone, you can use several ways to calculate the amount of water in a recipe. You can have more water or less water in any given recipe depending on your preferences and on what you want to do with the soap.

Remember -- the kinds and weights of fats and the weight of lye are fixed and unchanging for any given recipe; only the water can be tweaked to suit your liking.

The usual way soapers determine the amount of water is to use a setting called "water as % of oils". The default in most soap calculators is to use 38% water as % of oils. There are reasons why I don't recommend using this particular type of setting, so I'm going to stop here. I'll point you to a full explanation later.

Another (and IMO better) way of calculating the water is to use a setting called "lye concentration" or "water:lye ratio". Both of these mean the exact same thing; they just look a little different. My suggestion is to pick one and stick with it. I use lye concentration, so that's what I will talk about.

A common setting for lye concentration is the 30% you mentioned. I'd say a typical soap recipe for many soapers will have a lye concentration from 30% to 33%. Some use a little more water even -- a lye concentration of 27-28% perhaps -- and some use less water -- say a lye concentration of 40% or even higher. The most concentrated lye solution (least amount of water) you can choose is about 50% lye concentration. If you try to reduce the water to less that 50%, the lye won't dissolve properly.

So the shorter answer is -- a 30% lye concentration is one that is a pretty common one to use, but it's certainly not the only option. It would be a concentration I would be comfortable using if I wanted to do a swirl or other more complicated design using a reliable recipe. Other people might do the exact same recipe and design with a lye concentration ranging anywhere from 28% to 40%.