If you add 1 cup of borax to your laundry water at the beginning of the cycle, you can decrease the amount of detergent you use by half! Not only does this save you money and detergent, it also boosts the cleaning power of your laundry detergent.
I have been using Borax added to my detergent for many years. I use about 1/2 cup & find that sufficient. It really makes a difference especially on white clothes as I've had people comment on how white my socks get.