Last summer I made homemade laudry soap for the first time. Based on the small initial investment, and the large quantity of soap made from a small portion of those ingredients, I knew it was really CHEAP to make this soap. I never did the math though, and when telling anyone about it, I always said it broke down to pennies per load.
Well, I just ran out of the batch made last summer and had to start another one, so I did the math. I get 10 gallons of laundry soap for $1.21! It only takes 1/4 cup per load, so 640 loads to a 10 gallon batch makes it .00189 cents per load, not even a penny!! Not even half, or quarter of a penny! If I do 5 loads a week it's still not a full penny per week.
If you need to cut costs, I highly recommend this as one way to do it. It takes 15 minutes to mix it all up and then it sits for 24 hours, so it's not even labor intensive. Here's what I did:
Grate one bar of Zote soap (some use Ivory or Fels Naptha) and dissolve in hot water. I put it in a large pot on the stove, brought the water close to a boil, then added the grated soap and turned the temp down to low. I whisked it a few times while it dissolved. While this is happening, heat 2 gallons of water and add to a 5 gallon bucket. When the Zote is dissolved, add it to the bucket with 1 cup of washing soda, and 1/2 cup of borax. Whisk it all together to mix well, then add enough hot water to fill the bucket and stir once more. Put the lid on and let it sit for 24 hours. After that, use a smaller, handy container to hold your soap-perhaps an old laundry detergent bottle. Fill it halfway with the soap, then add water to fill the bottle. This is how you end up with 10 gallons of soap from a 5 gallon bucket. Shake it well prior to each use. Most directions I've read say to use hot water to fill the bottle, probably to break up the gelled soap.
Mine didn't gel this the first time, probably because I didn't have a lid for the bucket. I still used the soap though. My clothes come out clean. I didn't dillute the first batch though, but now that I think about it, just because it didn't gel didn't mean there was less soap, so I should have. I'd still have soap if I did!
More laundry recipes and a FAQ can be found here.