I truly adore Castile soap. I use it everyday of my life in some way, shape or form. Almost every one of my homemade cleaning products or homemade beauty products uses it. It is one of the most versatile soaps out available. As much as I love Castile soap, the cost can be prohibitive if I allow it to be. At a price of at least $10.00 per bottle, even using the smallest amounts can get expensive quickly. The solution to this potential high cost is learning how to make liquid Castile soap from a bar. For around half the cost – $5.00 or so – you can learn how to make a liquid Castile soap batch almost quadruple the size of the pre-made stuff!
It might seem complicated, but learning how to make homemade Castile soap isn’t hard at all. We use it so much that I generally end up doing one batch every week or so. It’s incredibly easy to make, but it’s also very budget friendly when you compare it to the other stuff. I buy my supplies from Grove Collaborative or Thrive Market usually. This allows me to grab the bars I need to make liquid Castile soap from a bar for around $5.00 per bar. If you’re new to Grove, sign up for a Grove account with THIS link and you’ll also get a FREE 5-piece Mrs. Meyers cleaning set with your first order of $25 or more.
How to Make Liquid Castile Soap from a Bar
Amazon is also a great place to find a deal on Castile bar soap. Usually you can buy multi-packs for just a few dollars per bar. The only other true cost I have is the water used and the power used. Since it doesn’t take much of either, the cost breaks down to around $5.00 per batch. At 96 ounces, that comes out to just $0.05 per ounce compared to an average of $0.50 per ounce for commercially made Castile soap.
When you make this homemade liquid Castile soap, you’ll use it in your homemade products just as you would the store bought stuff. Keep in mind though that you may need to thicken it in order to get it at a 1/1 measurement. It can be quite watery if you are not careful, but once you figure out how much water works for your family, you can use it in any recipe that calls for liquid Castile. If you need help learning how to thicken homemade soap, scroll to the bottom of this tutorial.
How to Make Soap from Scratch
If you are new to learning how to make soap, learning how to make homemade liquid Castile soap is one of the simplest soap recipes to start with. Because you start with a soap base that is already made and cured, it gives you the chance to figure out the in’s and out’s of basic soap making before jumping into the harder projects.
Once you’ve learned how to make soap from scratch with this homemade Castile soap recipe, you’ll be ready to take on more complicated DIY soap recipes such as these 33 homemade soap recipes. They are some of my favorites!
Homemade Liquid Castile Soap
This DIY liquid Castile soap is a great for DIY beauty recipes and DIY cleaners. I use it each time I make my homemade shave cream recipe, my DIY Dishwasher soap recipe, my DIY Liquid Castile soap laundry detergent, homemade coconut milk shampoo, my DIY makeup brush cleaner and many more. There are just so many uses for it! I usually make my batches unscented, however, if you’re looking to replicate something like Dr. Bronners Peppermint Castile soap, you can add a few drops of peppermint essential oil to get the scent you like.
You will need:
- 1 bar Castile Soap
- 6-12 cups hot water
- Cheese grater or small food processor
- Heavy Bottom Pot or 5-gallon bucket
- Wooden spoon
- Essential oils if you wish to add a scent
To begin making your homemade liquid Castile soap, grate the bar Castile soap with a cheese grater. Grating by hand can be really tiring for your hands so if you would rather use a small food processor, that is perfectly fine too. The smaller the grate or shred, the easier your bar soap will be to melt down.
If you don’t have a grater or a small food processor, simply use a sharp kitchen knife to cut the bar soap into chunks or shave the soap off in slivers.
Grate the entire bar of Castile soap into small shreds If you end up with a big-ish chunk of soap left over, like I often do, chop it roughly with a sharp kitchen knife so it does not go to waste. As I said a few seconds ago, the smaller your shreds are the quicker and more smooth they will melt down so use the small grate side of your cheese grater.
Heat 4-12 cups water until boiling. Add your finely grated soap to a heavy bottom pot or a 5-gallon bucket then slowly pour the boiling water over the soap. Be careful to pour slowly so you don’t risk burning yourself from an unexpected splash. Once the water is poured, use a wooden spoon to stir the bar soap shreds into the hot water until it melts.
If you’re using essential oils for scent, wait until the homemade liquid Castile soap is almost cool then stir in a few drops. Pour your finished liquid castile soap from a bar into mason jars or another container with a tight lid and use as normal. If you use essential oils, be sure to use a glass container since EO can degrade plastic.
If after making your homemade liquid castile soap, you find that your soap is too thin, you can thicken it by making a salt water solution. Add .5 oz regular table salt to 1.5 oz warm distilled water and stir until it is dissolved. Then, in very small amounts (1 ml or less), add to your soap and stir. Continue adding the salt water solution to your soap until you’ve got the consistency that you want.
*This post was originally published Feb. 2016. Updated April 2019.