How to Apply Sunscreen
How much for your face and when to reapply

How to apply sunscreen: start with how much

To cover your face and neck evenly you need about 1.5 mL. If that is hard to picture, squeeze a line along the full length of your index and middle fingers. That is roughly it.

It is more than most people expect. If spreading it all at once feels like too much, apply it in two layers. A thin first layer, a moment to settle, then a second pass covers the gaps.

The SPF on the label assumes a generous layer

Testing standards, including Korea's MFDS method, measure SPF with 2 mg of product per square centimeter of skin. So SPF 50 is the protection you can expect when you apply that full amount.

In real life most people are known to apply much less. When the amount falls short, protection falls below the label too, so getting the amount right matters more than chasing a higher number.

Do not skip your ears, neck and eye area

The ears, neck and the skin around the eyes are the spots people miss most. The skin there is thin and gets a lot of sun, so dark spots and fine lines can show up there first. After your face, sweep what is left on your hands over your ears and neck.

Reapplying sunscreen every two hours

Outdoors, reapply every two hours as a baseline. The American Academy of Dermatology (AAD) recommends the same. If you sweat heavily or swim, reapply right away no matter how long it has been.

Why reapply at all? Chemical filters break down a little as they absorb UV, and sweat, oil and rubbing from clothes wear the layer thin. Mineral filters wash off with water and sweat too, so every format needs a fresh coat.

• The first coat: apply it about 15 minutes before heading out, so chemical filters have time to settle on the skin.
• In the water: even water-resistant products need reapplying once the 40 or 80 minutes on the label are up.

How to reapply over makeup

Spreading sunscreen straight over foundation can make it slide. Sun sticks or sun cushions that you pat on are easier here. A stick also works well for small areas like under the eyes or along the nose.

Sprays are convenient but hard to apply evenly in the right amount. Rather than relying on a spray alone, apply a cream in the morning and use the spray as a top-up.

Do you need it indoors and on cloudy days?

If you sit by a window for long or step outside even briefly, yes. Ordinary window glass blocks most UVB but lets a good share of UVA through, and UVA reaches deep into skin and adds to dark spots and aging. Cloudy days are the same, since clouds do not block all UVA. If you are heading out, apply it as usual.

For what the SPF and PA numbers each mean, see What SPF and PA Mean.

Frequently asked questions

If I apply less sunscreen, do I get less protection?

Yes. The SPF on the label is measured with 2 mg per square centimeter of skin, so using less means less protection. If it is hard to apply that much at once, do it in two layers.

Do I need sunscreen indoors?

If you sit by a window for long or step outside even briefly, yes. Window glass blocks most UVB but lets a good share of UVA through. If you spend the whole day away from windows, it matters less.

How do I reapply sunscreen over makeup?

Sun sticks and sun cushions that you pat on disturb makeup less. Sprays are hard to apply evenly in the right amount, so use them alongside another format.

Do I need sunscreen on cloudy or rainy days?

Yes. Clouds and rain do not block all UVA. If you are heading out on a cloudy day, apply it as usual.