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How to make laundry soap

February 1, 2013 by Karl

laundry detergent photoberry berry berry berry


Why would anyone want to make their own laundry detergent?  The simple answer is money.  The cost savings are significant.  It costs about 20 cents per load using name brand detergent purchased at Wal-Mart.  It costs less than 3 cents per load to make your own.  In a home where two or more loads of laundry are being done every day this ads up quickly. Let’s say the average house does a conservative 10 loads per week.  That’s $2 per week, or $8 per month on laundry soap.  Making your own will chop this down to about $1 per month.

Laundry Soap 001-500

Here is the savings breakdown:

Fels Naptha: 2 bars – $2.98

Washing soda: 1 box – $3.49

Borax:  1 box – $4.79

Total laundry soap made with the above ingredients: 1536 ounces.

At 4 oz per load = 384 loads.

$11.26 / 384 loads = 2.9 cents per load.

All these materials are available in the laundry aisle of your local food store.

These numbers are actually VERY conservative.  The washing soda and borax will last much longer than the 1536 ounces of detergent in this example, but I wanted to draw some kind of simple comparison.

It only takes about 20 minutes to make 2 gallons of liquid laundry soap.  Why would a thrifty consumer NOT do this?

Here is the recipe:

1/3 bar of fels naptha soap (shredded)

1/2 cup washing soda

1/2 cup borax powder

Add six cups of water to a large pot.  Grate or shred the fels naptha (1/3 bar) into the water and heat the mixture until the soap melts, stirring constantly.  I use our food processor to grate the soap.  The soap is very hard and doesn’t grate easily on a hand grater.

Once the initial solution is dissolved, add the washing soda and borax to the pot.  Continue stirring constantly.  When all is dissolved, remove from heat.

Pour 4 cups hot water into a bucket (I use hot tap water).  Pour the soap mixture into the bucket and stir.  Now add cold water until you have two gallons total in the bucket.  (I mark the bucket ahead of time, using a milk jug to measure out a gallon of water from the tap).

Now, I stir the 2 gallon mixture and pour it into my waiting empty laundry detergent bottles (I picked some up at the local recycle station).

Shake before use.  You should use about 1/2 cup per load.

This recipe does a pretty good job washing our clothes.  We’ve been using this detergent for about two years now and have been very happy with the results.

How to make laundry soap from on Vimeo.

Don’t forget to check out our other money saving tips!


  1. Adele says:

    Hi Karl,

    Love the recipe! Have a question though…would this be ok
    to use in a “HE” (high efficiency) washing machine?

    Thank you!

    • Karl says:


      The short answer is YES. It’s fine in HE machines. The HE machines need low suds detergent and this recipe creates very little suds.

      I hope this helps!


  2. Karly says:

    Hi I’m just wondering about smell. Part of clean laundry is clean smelling laundry….does this have that? If not can things be added to improve the smell to make good smelling clothes?

    • Karl says:


      I would say that generally it would be considered “unscented” (at least when compared to the smelly big brands). I’m sure there is something you could put in to give you that laundry perfume smell, but one of the reasons I like to make soap is to get away from all those unneeded chemicals. I’m afraid I’m not much help on this one.

      By the way, I LOVE your name.


      • Kate says:

        Any kind of essential oil would do the trick Fels Naphta has a citrus smell to it if you don’t like it then try Zote its has a more floral scent i don’t like as many chemicals in it either but I prefer making it more because it is way cheaper then purchasing it. I usually grind a cup of Purex crystals and add it too. I also usually do the dry version as well combine grind and one to two tablespoons per load, but if the liquid works well if you want a more concentrated you can usually dilute the recipe up to a 5 gallon container.

  3. Athena says:

    Hi, can you use castle bar soap instead of the Fels?

    • Karl says:


      I’ve never tried it myself, but I have friends who have. They say it works fine. I kind of like the smell of the fels myself.

  4. Athena says:

    Thanks for the help, again (I think you were the one who helped me with my debate about if the castle soap I made would work out – it did 🙂

  5. Rebecca says:

    Hi Karl, just wondering if this could be also just used as a powder? I have used liquid washing machine detergent in past and found it too gloopy and my son doesn’t like using it. If I made this a liquid and added an essential oil could this be a dish detergent too? I’m waiting for my moulds to arrive and then I’m giving your soap recipe a go, I want to make the soap and liquid body wash and washing detergents. I have found your site a valuable tool and really easy to follow recipes. All the way from Australia- G’day mate!

    • Karl says:


      I know someone who makes their own powder soap, but I don’t believe this recipe is well suited for that purpose. I also wouldn’t recommend it for a dish detergent. Glad you have found my site useful! from USA- Catch y’all later! 🙂


  6. Richell Grant says:

    When I make my laundry soap I use Castile Soap and hot water with essential oils like Lavender or Eucalyptus.

    I boil 2 cups of water in my tea kettle, and while the water is boiling I cut one bar of soap and add it to a mason jar. When the water is nice and hot I pour it into the mason jar, be careful because it is VERY HOT! I will use a spoon to stir the water to help break down the soap. Then I add several drops of essential oil for a nice aroma. The jar goes a long way and here in Michigan (at Meijer) we can get 3 bars of soap for 3.59, however now that I have learned how to make the soap, I can save even more and make more too!

    Thank You!

  7. Pete S. says:

    After i followed your recipe, the next day may soap wasn’t thick or gooey like laundry soap is. As a matter of fact, it has separated at the bottom of the bucket. I stirred it up, yet it never thickened. It still is watery. Not sure what happened. the only thing that i can think of is that i let is sit in a cold basement, so not sure if the temp had something to do with it. I will try it again this eve and let it sit upstairs overnight.

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