The best vitamin C from Amazon: 65 products by price per capsule

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.

All other stores costs 61 % more per capsule than Amazon (€0.200/capsule against €0.124/capsule, 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: capsules per pack (median), products with declared additives.

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.