Skin terminal

Skin tools

How much sunscreen the skin you have uncovered needs, when an opened jar runs out, and what goes on first in the morning and at night.

How much sunscreen

The SPF on a label is measured at 2 milligrams per square centimetre of skin (ISO 24444). Most people apply a quarter to a half of that, and get a quarter to a half of the SPF. Tick what is uncovered.

About 0.22 teaspoon (1 mL) for the areas ticked.

Face, neck and ears alone come to about half a teaspoon; a whole body in a swimsuit is about an ounce, a shot glass. Reapply every two hours in the sun and after swimming or sweating, whatever the bottle says about water resistance. A 50 mL tube used on the face every day lasts about 46 days.

Today's UV index for your city → · Sunscreen and SPF moisturizers →

Use-by date, from the jar

Most cosmetics carry an open-jar symbol with a number of months (6M, 12M, 24M): the period after opening the maker vouches for. Enter the day you opened it.

Opened onSymbol on the jar

What goes on first

Thinnest to thickest, water before oil, sunscreen last in the morning. Skip any step you do not own; a routine of three is a routine.

Morning

Cleanser
Toner or essence
Vitamin C or other water-based serum
Eye cream
Moisturizer
Sunscreen (last, a full dose)
Makeup

Evening

Cleansing balm or oil (if wearing sunscreen or makeup)
Water-based cleanser
Toner or essence
Treatment: retinoid, or an acid, not both the same night
Eye cream
Serum
Moisturizer
Face oil or sleeping mask (if any)

Pairs people keep asking about: a retinoid and an exfoliating acid go on different nights, not the same one; vitamin C sits in the morning under sunscreen; benzoyl peroxide can oxidise a retinoid applied at the same time, so one in the morning and one at night. Wait a minute or two between layers only if the one before is still wet. This is the order the makers print on the boxes, not medical advice: a dermatologist's plan for your skin wins over any list.

Ingredient glossary → · Serums and treatments →