The problem with shelf price
Almost every external review of this category leads with the shelf price. IM8 Daily Ultimate Longevity is 149 dollars for a one-off order or from 119 dollars on subscription. DoNotAge's sachet product runs around 203 dollars per four-week supply. That framing makes DoNotAge look expensive and IM8 look moderate. It's not a wrong number, but it's the wrong comparison.
The comparison that matters
For every supplement in our database we compute two numbers that most reviewers don't:
- Price per gram of active substance, how much you pay per gram of the ingredients the product actually contains (excluding fillers and flavouring).
- Price per studied-dose day, how much it costs, per day, to hit the dose that was actually used in the clinical literature we cite.
The bottle price is the last thing that should decide this. The daily cost of hitting the studied dose is the first.
Worked example
IM8 Daily Ultimate Longevity's shelf price is 149 dollars for 30 servings. On our page that's $4.97 per research-dose day and $0.84 per gram of active substance. DoNotAge Pure NMN, at a much smaller sticker price for a single-ingredient product, hits its studied NMN dose at roughly $0.83 per day. The apples-to-apples comparison, the daily cost to hit the dose the literature actually studied, is not close.
Why we still don't rank purely on value
Value is 10% of our overall score, not 100%. A cheap product with the wrong dose or shaky evidence should not beat a well-formulated product on price alone. But the two numbers above are on every product page precisely so you can see the true cost of the thing that was actually studied, not the marketing price of the bottle.
How we compute it
We use the studied dose from the clinical paper we cite in the evidence block, not the label's suggested serving. If the label serving is lower than the studied dose, we scale the daily cost up accordingly and flag the product's dose-match % in the numbers strip at the top of the page.