Which Skincare Product Is Actually Better Value?

How we calculate skincare value

Three numbers do the work, and we show all of them — measured, not guessed:

• Cost per ml = price ÷ volume. Volumes in ounces are converted to millilitres first (1 oz = 29.5735 ml) so everything compares like-for-like.
• Cost per day = cost per ml × typical daily usage for that product type.
• Days of supply = volume ÷ daily usage, which also gives a rough bottles-per-year figure.

The daily-usage figures are standard estimates by product type — for example a serum at about 0.5 ml/day, a moisturiser at 0.75 ml/day, and sunscreen at ~1.25 ml for the face following the 2 mg/cm² application rule. Currency is display-only; the tool never converts between currencies.

Frequently asked questions

Why does cost per ml matter more than price?

Price only tells you what you pay at the till; cost per ml tells you what you pay per use. A larger or more concentrated bottle is often cheaper per ml even at a higher sticker price — and that’s the number that decides real value over a year.

How much serum should I use per application?

About a quarter of a millilitre — roughly two to three drops — once or twice a day, so around 0.5 ml daily. That’s the figure this calculator uses to estimate how long a serum lasts.

Is The Ordinary actually good value?

Usually yes on cost per ml — small bottles at low prices still tend to land at a low per-ml cost. But value also depends on how much you use and how long it lasts; enter the price and size here to compare it against any alternative directly.

How long does a 30ml serum last?

At typical usage of about 0.5 ml a day, a 30 ml serum lasts roughly 60 days — about six bottles a year. Heavier application shortens that; using it only once a day stretches it further. See the Product Expiry Tracker.