Beauty Calculators
Skincare cost per use.
Add each product in your routine with its price, size and how much you use. See what every application, day and month costs, and which products you will not finish before the period-after-opening symbol says to stop. Runs in your browser; nothing is sent or stored.
Your routine
Cost per use
Fill the form and press Calculate.
Worked example
A 30 ml serum costs $30. You use 0.5 ml twice a day. One bottle holds 30 / 0.5 = 60 uses, so it lasts 30 days. Cost per use = $30 / 60 = $0.50, $1.00 a day, about $30.44 a month. A 100 ml cream at $50 used 1 ml a day lasts 100 days. If its pack shows 3 months after opening (91.3 days), you use about 91% of it before that date and about $4.34 of the price goes unused.
How it works
cost per use = price / (size / amount per use). Days per bottle = (size / amount per use) / uses per day. Cost per month multiplies cost per day by 30.44 (a year divided by 12).
Wasted money. If you enter a PAO in months, the tool compares it with the days the bottle would take. When the bottle takes longer, the share you can use before that date is days allowed / days needed, and the rest of the price is shown as unused. That is a budgeting view only: it does not say a product becomes unsafe on that day, and it is your own reading of the pack.
Everything is arithmetic on numbers you type. No product prices or usage amounts are assumed.
Sources and basis (checked 2026-10-04): the period-after-opening open-jar symbol is defined in the EU Cosmetics Regulation (EC) No 1223/2009, Article 19(1)(d), and also appears on packs elsewhere; see our PAO calculator. EUR-Lex, Regulation (EC) No 1223/2009.
FAQ
How do I work out cost per use for skincare?
Divide the price by the number of uses in the bottle. Uses = size / amount per application. A $30, 30 ml serum used at 0.5 ml per application gives 60 uses and $0.50 per use.
What counts as one use?
Whatever you apply in one go: a pump, a pea-sized amount or a measured ml. Count it once, in the same unit as the bottle size. If you do not know, weigh the bottle on a kitchen scale before and after a week of use.
What is the PAO and why does it matter here?
PAO is the period-after-opening symbol, an open jar with a number of months. If a bottle would take longer than that to finish, the tool shows the share you would not finish in time and the money that represents.
Does a cheaper cost per use mean a better product?
No. This tool only measures money per application. It says nothing about how well a product works for your skin.
Does the routine total include every product?
It adds the cost per day, month and year of every product you enter. Products with an error are skipped and flagged.