What you'll need:
1 c. of Borax
1 c. of Super Washing Soda (you can usually find this at the larger grocery stores like Meijer or Walmart near the Borax. If you don't find it there you can sometimes get it at swimming pool supply stores or you can get it online at Amazon)
1 bar of soap like Fels Naptha, Zote or Ivory
1 grater (I recommend keeping one separate just for this purpose)
1 airtight container (we use an old coffee can with a tight fitting lid)
That's Arm and Hammer's Super Washing Soda in the picture, don't confuse it with baking soda. They are not the same thing.
Once you've gathered your supplies there are all of four steps left to homemade laundry detergent. Step 1: Grate your soap. Step 2: Add your washing soda. Step 3: Add your Borax. Step 4: Replace lid and shake it up, baby! There is an optional step 5: You can add a few drops of essential fragrance oil if you like. I use a "fresh linen" scented fragrance oil on occasion but you can add any scent you'd like.
The cost of making my own detergent breaks down like this:
The Borax costs me $3.29 for a 76oz. box= $0.34 per batch
The Super Washing Soda costs the same, $3.29, for a 55oz. box=$0.48 per batch
A three pack of Ivory soap costs $1.69.=$0.56 per batch
The grand total there ends up being about $1.38 for a batch. I use the full 2 Tbsp. per load and get about 32 loads of laundry out of one batch detergent. That puts me in at a crazy $0.04 per load of laundry!
Compare that to the Dynamo I used to buy before I started to make my own. For a 32 load bottle of Dynamo, I would normally pay about $9.87 at the grocery store. That's already $8.49 more than for the same number of loads with my homemade detergent. With the Dynamo the cost per load of laundry was about $0.31, more than six times the cost per load with the homemade detergent!
If I add the extra cost of essential fragrance oil to the mix I end up with a cost of about $1.47 per batch and still around $0.04 to $0.05 per load of laundry. No matter how you slice it, I'm saving a considerable amount of money for a small amount of effort. Definitely worth it.