(image from mysupermarket.co.uk)
This is the box of washing powder that I bought earlier in the year in some quantities because they were on half price offer at £6. A quick check here will tell you that Ocado [internet delivery service only] have it at half price right now, at Asda it is £9.50 and Sainsbury have it at £10 but Tesco and Waitrose currently sell it at "full" price of £12 a box. I am content that I got a bargain when I bought my six boxes.
I have been carefully measuring out my powder with an old Aldi yogurt pot, because I don't have a proper scoop. Each time I take a measure out of the box, I make a tally mark on the side of the box, and I also noted when I started the box, back on the 13th November.
Yesterday I did the 50th wash with the powder from the box.
There is still approximately 2kg [about half] of powder in the box!
This tells me that I was about right in my estimation that a box would last nearly two months; although I must be using less than they recommend, our clothes are coming out clean on a low-temp quick wash, though I do use a longer and hotter wash if the stuff is really dirty, which is rare.
Having bought the box for £6 and squeezing approximately 100 washes from each box is bringing each wash cost in at 6p - quite a contrast with 50 washes at £12, which would have made each wash four times as expensive at 24p! Definitely worth keeping track and doing the sums to see how we are doing.