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How to Re-size a Cold Process Soap Recipe

Learn How to Easily Re-size a Batch of Cold Process SoapI’ve had several people request a smaller sized cold process recipe for some of my most popular homemade soap recipes. However, as when I started making many of these specific soap recipes I had created, I always made larger batches to keep up with the demand from where I was selling at my local farmer’s market as well as Etsy. I’d never considered having to re-size a batch of cold process soap before. However, the solution is pretty simple.
How to Re-size a Cold Process Soap Recipe Using the Lye Calculator from Bramble Berry - Make a Large Batch Smaller and Vice Versa!

Bramble Berry’s lye calculator includes a tool that allows you to re-size any batch of soap. Simply plug in the existing recipe, choose the superfatting level and hit calculate. Then below the current batch label, simply choose re-size batch and enter in the size of batch you want to create! If you’re not sure what percentage the recipe was superfatted to, you can play around with the numbers until they’re close. (I typically use around 6% superfat.)

Pictured above is screen shot of the results from plugging in my Best Ever Big Lick Salt Bar Soap Recipe. This particular recipe fills three of my soap molds and yields approximately 30-36 bars depending on how large they are cut.

Re-sizing a Batch of Cold Process Soap - A Simple How To

As each one of my molds can hold a recipe with 36 oz. of oil, I plugged in 36 oz. under “resize batch” and then submitted the new information. It instantly converted the previous recipe to the smaller size with the new amounts needed. This new recipe will now fill just one of my soap molds instead of three and yield 10-12 bars of soap. (I tend to round up or round down the water amounts.) So for this recipe I would use 5 oz. of lye and 12 fluid ounces of water.

As this re-sized recipe is exactly one third of the larger sized batch, you would then divide the amounts for the fragrance oil and salt by 3. Therefore you end up using 2 oz. of fragrance oil. As the recipe calls for 1/2 cup of large sea salts, you would need to divide that by 3 as well. The easiest way to do this is to convert the 1/2 cup into Tablespoons. 16 Tablespoons equals one cup. So a half cup is the equivalent of 8 Tablespoons. 8 divided by 3 equals 2.6 Tablespoons. Therefore I would use 2 1/2 Tablespoons of salt. Or 2 Tablespoons and 1 1/2 teaspoons. (You can reference the original recipe and tutorial here.)

I hope this helps those of you just getting started out and in need of a little assistance. Math skills come in super handy when making soap. I’m constantly figuring percentages of oils I want to use in my new soap recipes. For more help with soapmaking as well as creating your own unique soap recipes, I highly recommend Susan Miller Cavitch’s book, The Soapmaker’s Companion. It was the first soapmaking book I ever purchased and the information has been invaluable.

For more great homemade soap recipes as well as bath and beauty DIY’s, be sure to follow my boards on Pinterest! You can also follow my blog on Blog Lovin‘.


  • Tiffany Barry

    September 25, 2013 at 11:27 am

    This is great! I’ve always wanted to try my hand at making soap, but most recipes I find are for larger quantities. I’d love to make some neutral smelling bars for my family to use. Thanks for this tool!

    Now… to work us the nerve to use it. 😉

  • Anne-Marie Faiola

    September 25, 2013 at 6:22 pm

    Thanks for the shout-out! I’m so glad that you’ve found the lye calculator and the resize batch to be so helpful. =)

    1. Rebecca D. Dillon

      September 29, 2013 at 2:02 pm

      You’re welcome!

  • Kalee

    September 28, 2013 at 12:15 pm

    Thank you for breaking it down! I would love to be able to do my own soaps because I have such sensitive skin! This is just what I needed!

  • Carl Richard

    February 7, 2014 at 2:34 pm

    Hello! My wife and I are new to soap making. We purchased some dairy goats for my nephew’s 4-H project and want to use the milk to make soap. We have a formula that we like, but don’t know how to make sure one batch will fill our molds. we have two tray molds one with 48 ounces of product (12 – 4 oz bars) and one with 30 ounces of product (15 – 2 oz bars) we would like to add a kids mold as well that makes 8 ounces of product (4 – 2 oz bars). so my question is what do i enter into the resizer to get these amounts? It gives a total volume so should i fudge the amounts of fats to get the total volume 48, 30 or 8 ounces respectively?

    1. Rebecca D. Dillon

      February 8, 2014 at 4:40 pm

      To determine the amount of oils needed for any mold, calculate the mold length times its height, times width. This is the volume. Multiply that number by .39 . The answer will be the amount of oils needed for that batch of soap.

      1. Carl Richard

        February 9, 2014 at 2:46 pm

        Great! Thank you that helps. Just to make sure I have it right for example the 30 ounce mold would be 11.7 ounces of oils to fill the mold.

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