Amazon or Prozis for whey isolate: which is better value per kg

The median is not the price you will pay. It is the midpoint of that store’s catalogue in this category, and it tells you whether a store is dear or cheap overall. For buying, the specific row in the table below is what counts.

Price per kilo does not tell you how much active ingredient is inside the kilo. This table does: for each ingredient, the median dose per serving at each store and how many products reach the dose backed by studies (the same reference this site scores with).

The dose is per serving, not per tub. A big tub with a short dose forces you to take two scoops to get the same, and then it lasts half as long: that is why the price per dose in the next section does not match the price per kilo.

Prozis costs 38 % more per kg than Amazon (€75.54/kg against €54.88/kg, medians of both catalogues). That difference does not come out of nowhere. These are the data that explain it, with each store’s figure alongside: pack size (median), different brands in the catalogue.

None of these factors is an accusation. They are medians of what each store publishes on its pages on the day prices were collected: where a page does not declare a figure, that store does not count in that row instead of counting as a zero. A specific product can contradict its store’s median, and that is what the full table is for. How all of this is calculated.