How to compare cost per serving

It is the simplest calculation in this market and the one most likely to change your mind. Divide the price by the number of servings in the pack. That is it.

A £58 tin with 30 servings costs £1.93 a day. A £27 tub with 60 servings costs 45p. Those two products can sit next to each other on the same shelf with similar front-of-pack claims.

Four adjustments worth making

• Normalise the active amount. If one collagen powder gives 10g and another 5g, compare cost per 10g, not cost per scoop. Otherwise you are rewarding the smaller serving.
• Use the subscription price if you will actually subscribe. A 20% subscription discount is real money, but only if you would have kept buying it anyway.
• Check the lowest in-stock retailer price, not the brand price. On this platform the spread between retailers on the same product is often 15% or more.
• Account for how long it takes. Joint formulas are usually assessed over three months. Compare the three-month cost rather than a single pack.

What cost per serving does not tell you

It is a price metric, not a quality metric. A cheaper cost per serving on a product with an undisclosed blend is not obviously a better buy than a costlier one where every amount is printed. Batch testing, sourcing transparency and packaging all cost money and some of that cost is buying you something real.

The useful discipline is to compare cost per serving between products you have already decided are acceptable on the things you care about, rather than using it to pick from the whole shelf.