How to Make Liquid Castile Soap from a Bar

This post may contain affiliate or referral links that help keep this site running. For more information about this, please see our disclosure policy.

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!

How to make liquid castile soap - Are you learning how to make soap? This homemade liquid castile soap from a bar is super easy and works just like the more expensive stuff! You'll spend over 50% less on Castile soap with this method!


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:




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.

Six Dollar Family - Frugal Living, Family Recipes, DIY & More
Closed group · 2,559 members
Join Group
We do NOT accept profiles that were created in 2018. If you do not have a "real" name, you will not be accepted. Are you working toward being a Six ...
Follow Me

Stacy Williams

Stacy Williams is a 37-year old wife to a USAF Gulf War Veteran, mother of two teen girls and fur-mamma to a rescued pit bull. The face and brain behind the frugal living and lifestyle blog Six Dollar Family, she also owns and manages Long Haul Wife, Republic Preparedness, The Genealogy Queen and a handful of others sites. By the age of 30, Stacy had overcome a drinking problem, a drug addiction, divorce, survived domestic violence, and had built a life for herself and her daughter after spending 10 months in a homeless shelter. Stacy is passionate about homeless advocacy and addiction education.  Her first book, also called Six Dollar Family is available on Amazon.

Learn how to earn a full-time income from home by learning how to start a blog just like this one! Click HERE to check out Stacy's step-by-step tutorial.
Follow Me

Latest posts by Stacy Williams (see all)


  1. MichalMichiels says

    Can you use this liquid castille soap for your laundry detergent recipe? Or Castille bar soap?

  2. When you say “one bar,” do you mean 4 oz? Thanks!

  3. When making dishwasher detergent, when do I add the Castile soap?

  4. I have only 6 cups of water, and have already used two bars of soap, but it’s still really watery. What am I doing wrong?

    • Tiffany, pour off some of the water (into a bowl so that you don’t waste the soap that is in it) and let the rest come to a simmer over medium/low heat. Simmer until the water and soap combine then try adding the rest of the water and heating until it combines. I’ve never had to do it that way personally, but I have a close friend who needs to every time.

    • Thank you Stacy. I tried this and came up with the same result. But I realize that maybe my question wasn’t clear enough.
      I suppose that my expected result would be something similarly as thick as the hand soap from the grocery store (not exactly, but close). But I am thinking now that something else must be thickening that soap up. Maybe a chemical?
      The soap is fine, it’s just really watery. I had made your shampoo recipe, and even with the added oils (of course I know that water and oil don’t mix) it was just like pouring water on my hair, and it was difficult to lather in. I thought maybe because the soap was too thin.

      • Tiffany, you can make a salt/water solution to thicken them if you’re not happy with the consistency. Mix 1/2 oz of regular table salt to 1 1/2 oz of water and stir until the salt is fully dissolved. Add it to your finished product in very small amounts until you get the consistency that you’re looking for. It usually doesn’t take over a ML or two to get it to thicken up. It will work for any of our recipes, hand soaps and shampoo included. 🙂

  5. Why is my soap so thick with a weird slimy consistency? I used 1 bar of Dr. Brominers to 9 cups of purified water heated on the stove. I let it cool and then the next day it was almost solid with a slimy consistency after I stirred it. This is my 2nd attempt. (Love the laundry detergent by the way) I plan on trying most of your recipes.

    • I’ve never had that happen. Try putting it back on the stove and adding 2-3 more cups of water. Because stoves heat at different temps, some folks will need more water than others.

  6. Jenny Fortgens says

    Thank you for your recipe, it is awesome! I did had to add more water to it, for the same reason as Stacy

  7. Just bought the Kirk’s castile 4 oz bars for a much lower price from Walmart. I had to buy it online and pay shipping but it was still cheaper than any other place online, including Amazon. Can’t wait to try this recipe.

    • Thanks for letting us know! I link to them so that folks who can’t find it in store can still pick it up. 🙂 Glad to know that Kirk’s is cheaper. I’ve never tried it though. Let us know how it goes!

  8. Susan Rutledge says

    So when you store the soap in a mason jar, does it solidify again after it cools down?

    • Stacy Barr says

      Susan, it can, but doesn’t always. If it happens to, simply add it back to the pot and add a bit more water. It’s different each time I make it so I really have no idea what will make one batch gel and another not gel.

  9. A tip for anyone grating soap: I invested in one of those hand crank graters (I think it’s IKEA brand, but I bought it on Amazon for around $10). No accidentally grating your fingers or having to deal with those tiny ends of bars! I keep it stashed with my other laundry detergent ingredients, so we don’t use it on food.

  10. Can I use any soap bar here?

  11. Why does it say 4-12c of water? How will it be the correct concentration if I vary the water?

    • Stacy Barr says

      The water amount is varied because each person will want theirs a bit thinner or thicker than the next person.

  12. Hi, thank you for this recipe. Is bacteria a worry bc some recipes (with ingredients of castille soap) call for distilled water.

    • Distilled is used for purity from chemicals such as chlorine. As long as you follow the directions and use an air tight container for your recipes, you should be fine to use it within a reasonable time.

Speak Your Mind


This site uses Akismet to reduce spam. Learn how your comment data is processed.