Daylene Alford· Registered
This calculation is incorrect because the 55oz of washing soda is dry weight while cups are fluid measures. In order to get the correct measurement you must weight a cup of washing soda which I did. One cup of washing soda is 9.8 oz (yes, I did zero the scale with the weight of the cup before adding the soda). This may vary a quite a bit depending on the density of the soda and/or variations in measuring utensils. For example one of my cup measures is larger then all the others. This means that a 55oz box of washing soda has about 5.6 cups not 6.875.76oz box = 9.5 cups
55 oz box = 6.875 cups
Now borax only weights 6oz for 1cup so in a 76oz box you get 12.67 cups.
I know this post is old but it showed up as a first result when I googled this so I thought I would go ahead and post so people aren't finding incorrect information.