Typically, I like to use liquid detergent, but the recipes for this kind require boiling soap and I wanted something that was quick and wouldn't smell up the house. Sew Much Ado is a great blog for primarily sewing projects, but she had a detergent recipe that she came up with after trying several different ones. I took her word for it, and chose to use this one. You can find her post here where you'll also find a label print out for your detergent container, if you decide to make your own.
Homemade Laundry Detergent
1 cup Borax
1 cup Washing Soda (this is different from baking soda)
1/4 cup Baking Soda
1 bar Fels-Naptha soap
Directions: Using a sharp knife, cut the Fels-Naptha bar of soap into large chunks and then place those in a food processor.
Grind this into a coarse powder. (You can also grate the soap first, and then place it in the food processor; I did it both ways and preferred just using the processor because it took less time).
Stir all ingredients in a large bowl. Store in an airtight container. Use 2 tablespoons per load of laundry.
One batch of this will yield approximately 36 loads, and after calculating the costs, one batch cost $1.81, which comes out to $0.05 a load. I find this to be a great price, plus the ingredients are all natural, so even the most sensitive skinned people should handle it well.
*The Fels-Naptha is a fragrance free soap, but it does still have a strong soapy smell. If you should decide to make this, and smells bother you, you've been forewarned.