I had done a similar calculation on my box of Color Megaperls and came up with $0.20 per tablespoon.

I just weighed a flat tablespoon of Persil Universal Megaperls at 11.74 grams. Measuring to grams gives a much more accurate measurement than ounces. That means a 3.038 kg box contains 260 Tbsp. Using these numbers you should get closer to 87 washes out of a single box. Using the $41.99 online price at Better Products Online for a 3.038 kg box, your value is closer to 48 cents per load using my calculations.

Henkel bases the number of loads on a 67.5 gram dose (divide a 3,038 g box by 45 loads). At 11.74 g/Tbsp, that comes to 5.75 tablespoons per dose. Since 1 Tbsp = 14.79 ml, 5.75 Tbsp = 85 ml. So it would appear that Henkel bases the number of loads on an 85 ml "middle of the road" dose that is right in the center of its dosage chart.

Cost per tablespoon is somewhere around 15 cents.

Well, I feel a lot better about using Persil at 50 cents a load than I do at 76 cents a load. Thanks for the calculations. I really love the detergent - it is the only detergent that I am 100% happy with, but it is expensive.

I have used Persil before and love it. It cleaned my whites and removed old stains too. So if it can do that for me, then the cost of it is not a problem. One thing I noticed about persil, is that it rinses out really well, the best of any detergent I have ever used.