Four numbers decide whether a supplement is worth buying. Most labels put three of them on the front and hide the fourth.
A supplement label has to tell you the truth. It does not have to tell you the truth in the order that is useful to you.
Here are the four, and here is where each one hides.
1. The amount of active ingredient per serving
Front of the bottle, usually the largest number on the label. This is the one everybody shows, because a big number looks like a good number.
It is only meaningful next to the next three.
2. The serving size
Buried in the Supplement Facts panel, in small type, above the ingredient list.
This is the number that makes the first one honest or misleading. A "1,200mg" front label might mean one capsule or four. If it takes four capsules to reach the dose, the bottle empties four times faster than you assumed.
3. Servings per container
Directly under the serving size, and almost never on the front.
Front-of-bottle capsule counts are not servings. A bottle of 90 capsules at three capsules per serving is 30 servings — a month, not three.
4. Cost per serving
Not on the label at all. You have to work it out.
Price ÷ servings per container = what one dose actually costs.
This is the only number that lets you compare two products, and it is the only one no brand is required to print. We put it on every product card and every product page.
Working an example
Two berberine products, both real formats you will find:
| Product A | Product B | |
|---|---|---|
| Front of bottle | 500mg | 1,200mg |
| Capsules | 90 | 60 |
| Serving size | 1 capsule | 2 capsules |
| Servings | 90 | 30 |
| Price | $37.99 | $24.99 |
| Per serving | $0.42 | $0.83 |
Product A looks cheaper per serving and has more capsules. But its serving is 500mg against B's 1,200mg. To take the same amount you need 2.4 of A's servings, which costs $1.01 — more than B's $0.83, from a bottle that holds 37 full doses, not 90.
Nothing on Product A's label is untrue. The comparison is just not the one the packaging invites you to make.
What to do with this
Ignore the front of the bottle. Find the Supplement Facts panel, read the serving size and servings per container, then divide the price by the servings. That number is the product.
Two things that complicate the arithmetic have their own pages: what a clinical dose actually means, and why a mineral's compound weight is not its dose.