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Six years ago, we decided to try our hand at making our own laundry detergent. It started as an experiment in saving some money, but then something happened – we never stopped. It’s cost effective and we like that this mixture leaves our clothes clean without the heavy scent of ‘mountains’ or ‘fields of flowers,’ but most importantly, it works! The lack of perfumes and dyes is friendly for the allergy prone (aka, us and every single animal that lives in this house!), and we’ve used it in both a standard washer and, most recently, our H/E machine, too.

There are just 3 ingredients to the recipe – borax, washing soda and a bar of Fels Naptha soap – and all of these items can usually be found in the grocery store, in the same aisle where you’d buy the big name detergent brands (often times, you’ll find them tucked on the lowest shelf). The longest part of the process has always been grating the bar of soap to make the dry mix, but many of you recommended the microwave method, claiming that it saves your arms a workout. (I’ll take that!) A few months ago, I tried this new-to-me method for the first time and shared the process in an Instagram Story, and we received so many questions, I thought I’d share over here just how easy it is to replicate.

I always make a double batch at once, but whether you’re making two batches or five, the math is simple: 1 bar of Fels Naptha + 1 cup borax + 1 cup washing soda = DIY laundry detergent. In the past, I used a cheese grater to whittle down my soap, but the microwave method nixes that step altogether!

Here’s How:

Cut up the bars into thirds or fourths, and put them on a microwave safe plate. Microwave for 2-3 minutes, and allow them to cool for up to one hour in the microwave. It’s so important to leave them be, because not only will the soap be extremely hot, but the strong smell of Fels Naptha will dissipate the longer it’s left untouched.

In the meantime, mix equal parts borax and washing soda in a large bowl. If you used a single bar of soap, you’ll use 1 cup of each. If you used two bars of soap, you’ll use 2 cups of each – and so on.

Once the soap has cooled, take it out of the microwave. Each chunk should have ballooned into twice its original size. (It’s weirdly magical. Science!) Toss them into a quart bag, and pound with a fist. The soap will easily crumble into a fine powder, and it can then be whisked together with the borax and washing soda mix:

That’s it!

Our double batch fits perfectly in one of these glass jars (we use these jars for everything from stashing coffee to cat food!), and we keep this 2 tablespoon scoop inside.

Only 1 tablespoon is needed for a regular load, but toss in a small amount more for larger loads. We currently have a H/E washing machine, and we’ve had great success putting the soap mix right into the detergent tray, although others swear by adding the detergent right into the drum along with the clothes. Tip: Resist the urge to use more than you need, as too much can dull your clothes! 

Since completing the laundry room renovation, we also keep a wedge of Fels out by the sink. It has been an absolute miracle as a stain pre-treater; simply run it under water and rub it into anything stubborn. Before washing any of our dog bed covers, I’ll take a moment to pre-treat the worn down areas, and they always come out of the wash looking great.

Some of our readers have swapped in Kirk’s Castile, Zote or Ivory in place of the Fels Naptha, and we’ve even heard of using OxiClean as an additional whitening boost! For anyone who may be having trouble finding the ingredients at your local grocer, you can get a starter pack right here. One box of both borax and washing soda will yield you many, many batches of detergent (we only buy these two ingredients maybe once a year), so we’re always sure to stock up on bars of the Fels Naptha soap.

Happy washing!

39 replies on “Make Your Own Laundry Soap (Using the Microwave Method!)”

    1. Before we switched to the microwave method, we used the fine grater disc and our food processor. You have to rinse it pretty thoroughly before using it for food, but it’s not that bad.

    2. Another great tip for grating soap is to use one of those rotary cheese graters with a handle, or if you’re lucky to find a Salad Shooter (remember those?) at a thrift store, use that!

  1. Can’t wait to try this. I love that it’s natural and cheap:) My two favorite things!! Thanks for the info.

  2. Dying to try this! It looks so simple and bonus of it looking pretty in the glass jar. :)

  3. I double the batch and use one bar of Fels Naptha and one bar of Dr. Bronners Eucalyptus. We don’t have sensitive skin in this house so it makes it smell even better without being to Mountain Fresh. I’ve been cutting the soap into smaller chunks in pulsing in our food processor which works great!

      1. I should have proofread my comment. *too mountain fresh *and pulsing.

        So embarrassed ?

  4. In a separate jar, mix a cup of salt (regular salt works, but Epsom does too – if you have hard water, stick to regular) and 20-30 drops of essential oils, toss in the drum of the washer before adding your clothes and you have a natural fabric softener, too!

      1. Great tip! We already use white vinegar in the bleach compartment, but haven’t tried essential oils. Maybe that’s our next experiment!

    1. Do you put the entire cup of salt in for each load, or some smaller quantity? Thanks.

        1. Sorry – question was directed at Kate’s comment. Her essential oils idea is to mix them with a cup of salt.

    1. I second this. Good information. The Think Dirty app is a great tool if you’re looking to reduce unnecessary chemicals in your home.

  5. Hi, I live in Florida and spices, etc. get hardened because of the high humidity. Also, I have Oxi Clean powder that is hard as a rock. I have to use an ice pick to get small chunks off for the laundry. I’m guessing this mixture will harden up as well – thoughts?

      1. Another Floridian here. As long as you keep the laundry soap in a closed container(same goes for the oxiclean) you shouldn’t have any issues.

    1. I’m from deep south GA and I never had problems with mine DIY laundry soap hardening up. If you have a good airtight container it shouldn’t be a problem.

  6. Yes! I’ve been using this same recipe for a long time too, but was so happy to see your Instastory awhile back with the microwave tip. It has made the process so much better, and I feel like the ingredients mix better too, now I don’t have big sections of my container of just the Felz.

  7. It is usually the scent of detergent that bothers me. Is the soap scented. I use dye/scent free detergent, but it is definitely not chemical free. Also, is the vinegar a necessary part of the process or a choice for additional cleaning/softening power?

    1. The soap has a very mild scent, although it’s pretty strong once microwaved (which is why I strongly recommend allowing it to cool for an hour). However, the clothes have little to no scent once washed and pulled from the dryer!

        1. Hello! I am so excited to try this. Can you please tell me about your vinegar use?, i.e., how much do you use and what do you think the benefits are? Thank you so much! I have never heard of making your own detergent before.

          1. We use maybe a half cup (or whatever the ‘max’ line is), and we pour it right into the bleach tray. People use it as a softener, although we’ve always thought that it helps to brighten white!

  8. I noticed that you have wool dryer balls. Do you use dark ones with your dark clothes or have you noted any shedding of “whie fiber” when using the light colored ones in your darker loads?

  9. OMG whaaaat?! I had no idea that making your own laundry detergent was really a thing. Once we get back to our house (the contractors kicked us out, sad face) I’m TOTALLY doing this! I am so over my clothes smelling like a tropical flower explosion! Thanks for sharing, I’ve bookmarked this post :)

  10. It just occurred to me that I’ve been following your wonderful blog for 6 years! The original laundry soap post was the first thing I ever found on pinterest and it led me here to you! It’s hard to fathom all of the changes that have happened during those years but I’ll always be an avid follower, so thank you for letting us be apart of your journey! Much love to you all :)

  11. I LOVE THIS POST! I have used this laundry soap recipe for years and love it so much…. except for the grating of the soap. I need to make a new batch soon, so I will be trying this method!! thank you for rescuing my arm from the tireless grating!!!

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