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A mason jar filled with pale amber liquid soap with a black pump dispenser lid, sitting on a white cloth on a wooden surface with flowers in the background.
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Basic Liquid Soap Recipe

Coconut oil creates the abundant bubbles and cleaning power, while the olive oil and 5% superfat keep the formula gentle and moisturizing rather than stripping your skin.
Prep Time30 minutes
Cook Time40 minutes
Cooking3 hours
Total Time4 hours 10 minutes
Course: Pantry Staple
Servings: 1 quart soap paste (make 1/2 gallon soap)
Author: Katie

Equipment

  • Slow cooker or very large pot
  • Stick blender
  • Heat-safe glass or plastic container for mixing lye
  • Stainless steel or heatproof plastic mixing spoon
  • Gloves, goggles, and safety gear
  • Scale (for accurate weighing)
  • Thermometer
  • Plastic sheeting + bungee cord (optional, for sealed cook method)
  • Mason jars or bottles for storage

Ingredients

Instructions

  • Make the Lye Solution. Put on gloves and goggles for safety. Weigh 264g (9.3 oz) of KOH and 834g (29.4 oz) of water separately. Slowly add the KOH to the water (NEVER the other way around).Stir until fully dissolved. The solution will get very hot you will also hear a crackling sound as you stir. All normal! Set aside in a very place to cool.
    Side-by-side images of a glass measuring cup - empty on the left and filled with a cloudy liquid (lye solution) on the right
  • Heat the Oils. Weigh and add 900g (31.75 oz) of coconut oil and 100g (3.5 oz) of olive oil into a slow cooker or stainless steel pot. Turn slow cooker on high to let melt directly in there. To speed up the process, melt the oils in a pan on the stovetop on low.
    A three-panel progression showing coconut oil being melted in a pot - from solid white coconut oil on the left, to partially melted in the middle, to completely liquefied oil on the right with a pink silicone spatula.
  • Let both components cool. Let the lye water cool down until it is clear, not cloudy. Let the oils cool slightly until the pan or slow cooker is warm but not too hot to the touch.
    a large stainless steel pot with melted oils and an empty Pyrex measuring cup.
  • Mix the Lye Solution with Oils. Slowly pour the cooled lye solution into the melted oils. If you’re using the alcohol, add it now. Begin mixing with a stick blender in short bursts until it is well combined. If you aren’t using the alcohol this will take awhile and you may only reach a thin trace. If you are, it will go a bit faster. Make completely sure there are no visible spots of oil before moving on to the next step.
    process of blending to trace: A three-panel progression showing the liquid soap's consistency changing over time - from an amber-colored liquid with bubbles on the left, to a stirred middle stage, to a creamy, lighter-colored final product on the right
  • Cook the Soap Paste. Turn the slow cooker to medium or high heat or set large pot on very low heat on electric stove or hot plate. Place the soap batter inside and cover. Cover the slow cooker with plastic sheeting and secure it tightly with a bungee cord (optional, this makes sure the alcohol does not evaporate off and keeps the heat in.) (Do not use gas.) Stir occasionally while cooking for 2–3 hours, until the mixture becomes thick and translucent. The soap is ready when it reaches a gel-like, translucent consistency and passes the zap test. It will be relatively solid, like playdoh. If there’s still liquid in there, keep cooking. Note: some people like to weigh the full pot before and after cooking, then add more alcohol in to replace any that burns off. I don’t do this, but just accept a small amount will evaporate.
    Three-image progression showing the soap-making process in a slow cooker - starting with liquid ingredients, then showing gradual thickening and transformation into a translucent gel-like soap paste.
  • Store Paste. This process leaves you with a paste that you will then dilute to use as a finished product. I prefer to store the gel paste and then dilute it as I need it. But if you’d like to dilute the whole batch, you can.
    Side-by-side images of soap-making process - a white bowl containing translucent soap paste being lifted with a wooden spoon, and a small green glass container of the finished soap paste with a wooden spoon.
  • Dilute. Be aware that if you don’t go through your soap quickly, mold is a possibility once water is added. The general rule of dilution is: 1 part distilled water to 1 part soap paste. You can heat the water and blend it if you’re in a hurry, but I just let it sit overnight and it’s diluted in the morning. Go slowly, it’s always easy to add more water.
    Side-by-side images showing a mason jar with translucent gel-like soap and a plastic container with the same soap topped with a purple lid.
  • Add color or fragrance if desired. Add essential oil, fragrance oil, or liquid colorant if desired. The amount needed will depend on the specific oil.
    Side-by-side images showing a hand holding a brown bottle (likely essential oil) next to a jar of liquid soap with a purple lid, and the completed soap with the lid closed.
  • Bottle and Store. Pour the finished soap into pump bottles, mason jars, or dispensers. It will be cloudy at first but will become clearer over the next 1-2 weeks.
    Close-up of a Ball mason jar with amber liquid soap,

Notes

Commercial soaps have a lot of glycerin and other additives to make them thicker, so this will seem thin to you.  But don't use too much, there's still lots of lather and cleansing properties. 
This is slightly lower in lye than most liquid soap formulas which keeps it gentle on your skin and good for the whole family. But because of this it will never be crystal clear.
You can do this on a stovetop on very low heat, but it’s quite dangerous. You’ll need to trim the plastic and keep an extremely close eye on everything. At some point the soap with puff up as it cooks, and if any leaks out, the alcohol in it makes it very flammable. I don’t recommend it.