Two bottles for a hundred and thirty-eight dollars. A tub for fifty-four. A ninety count for thirty-nine. Which is cheaper? You cannot tell, and that is not an accident of retail; it is what the packaging is for.
The three numbers you need
Price paid, servings in the package, and servings taken per day. Divide the first by the second, multiply by the third, and you have a cost per day that can be compared with anything else on the shelf, in any format, at any bundle size.
Worked on this product: the two bottle order is a hundred and thirty-eight dollars for sixty capsules at one a day, which is two dollars thirty a day. The three bottle order is a hundred and seventy-seven for ninety days, a dollar ninety-seven. The six is two hundred and ninety-four for a hundred and eighty days, a dollar sixty-three.
Where the trick usually hides
In the serving size, almost always. A ninety capsule bottle at thirty-nine dollars looks like excellent value until the panel says three capsules per serving, at which point it is a thirty day bottle costing a dollar thirty a day, and the comparison you made on the shelf was wrong by a factor of three.
Check the serving size before the price. It takes two seconds and it is the single most useful habit anyone can have in this aisle.
What the per-day figure is really telling you
A total price is a decision about one afternoon. A per-day price is a decision about a habit, and a supplement is a habit or it is nothing. Two dollars thirty a day is a coffee you did not buy. A dollar sixty-three is less than that. Framed as a hundred and thirty-eight or two hundred and ninety-four dollars, the same commitments feel entirely different, which is exactly why checkouts show you the total.
The bit the arithmetic does not cover
The cheapest per day is always the largest bundle, and the largest bundle is also the largest amount of money at risk in one payment. On this product the six bottle order runs a hundred and eighty days while the refund window runs sixty, so the decision about whether to continue arrives about a third of the way through the supply.
That is not a catch and nobody is hiding it, but it is a real consideration and the checkout will not do it for you. If you are unsure whether the product suits you, the smaller bundle costs more per day and less to be wrong about.
The three orders are compared line by line on the pricing page.
