I just started making my own laundry detergent because it’s much cheaper, but something about it is making my laundry softer, too. Here’s the recipe I used for a dry mix:
1 bar Fels Naptha soap
1-1/4 c. 20 Mule Team Borax
1-1/4 c. Arm & Hammer Washing Soda (not baking soda)
Grate the soap with the small holes of a grater. Stir everything together. I used an old ice cream bucket. Use 2 tablespoons (I use a scant ¼ cup measure) per load.
I was worried it wouldn’t dissolve, but it does even though I almost always use cold water (except diapers and wet sheets!). It doesn’t bubble up like commercial stuff would, but it still works.
Someone else's calculations came up with a cost of just over a penny a load.