Question about soap weights

Soapmaking Forum

Help Support Soapmaking Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.


Well-Known Member
Mar 13, 2016
Reaction score
Let me start by saying I am not looking to sell my soaps! I've been looking at all the beautiful soaps and packages and notice most have a weight printed on them. How do you get each bar to be exactly the same weight? Even when I use individual molds not every bar is exactly the same amount. Do you sellers have to weigh each individual bar and custom print each label, or do you measure it as you pour for exact weights? How does that work for bars cut off a log? Teach me, oh wise ones! :mrgreen:
I also label using the minimum weight of the bar. Most of my bars are several tenths of an ounce (up to a full oz.) over what the label states. I do sell my soaps, but I always cure them 4-6 weeks (or longer) before I package them. Soaps can continue to lose "water weight" for several months, so the net weight can change over time depending on the recipe.
It's supposed to be the weight of the soap itself at the time of sale, but that's impractical, so I do what the others do. Weigh the lightest bar and take a little more off for continuing weight loss as time goes on -- that's my net weight for all bars in the batch. When I package the bars after a minimum 4 week cure, most are 1/2 to 1 oz over the minimum.

Even if you use a consistent batch weight, level out the soap batter in the mold, and cut as consistently as possible, it's really easy to get 1/4 ounce variation or more from bar to bar. If you like swoopy tops and such, that will add to the differences in weight.

When I was figuring out my batch size for a specific mold, I decided I wanted to shoot for a minimum net weight of 4.5 oz, so I worked on tweaking my batch size for that particular mold so the bars weigh enough when freshly cut to be comfortably over 4.5 oz when they're packaged. Except for the time I had to trim the tops off the bars because the tops were ridiculously ugly, this works pretty good.
Last edited:
Ah got it! Here I was thinking there was some neat trick to getting all your soaps the same weight lol. It more of a minimum weight type thing. Thanks!
I weight 10 bars of the same soap and the average it out and roll that number to the nearest whole ounce.

Which will not give you actual net weight. Does not take long to weigh each bar while packaging

What's wrong with his procedure is that you can't use the average. Having some overweight packages doesn't make up for the ones that are short. It would have to be the minimum.

There's nothing wrong with the way you do it, but not everyone will want to assign an individual weight, like meat.

Drying is the complicating factor for all of it. There seems to be an allowance in the law for that sort of weigh change, but I haven't seen any specifics for how it's applied to soap, if there are any.
I use the e symbol and weigh each soap to ensure that it conforms. As the bars are cut with a uniform cutter in a standard mould, they don't really deviate from the standard. On the odd occasion the bars are enough underweight to not conform, I stick a sticky label over the pre printed weight with the lower weight on and put them in a bargain box at a lower price.