Sunscreen Basics: What SPF Means and Why You Reapply
Sunscreen is the least glamorous and most useful product most people own. The two things that matter are using enough and using it again.
What SPF describes
Sunscreen helps protect skin from part of the sun's ultraviolet radiation. The SPF number refers mainly to protection from the UVB that causes sunburn. A separate rating, often shown as "broad spectrum" or with a UVA mark, tells you it also covers the UVA linked to longer-term skin ageing. You want both.
Enough is more than people use
Most of the protection a sunscreen can give depends on applying a generous, even layer. A thin smear gives far less than the label suggests, because the rating assumes a full amount. For the face and neck, a common guide is about two finger-lengths of product, adjusted to your own size.
Why reapplication matters
- Sweating, swimming and towelling all remove sunscreen.
- It also wears down through the day with normal touching and rubbing.
- Reapplying through a day outdoors keeps the layer doing its job; one morning application is not a whole-day shield.
Fitting it into a routine
Sunscreen goes on last in a morning skincare routine, after moisturiser and before make-up. Let it settle for a minute. Texture and finish vary a lot between products, so if you dislike one, try another rather than skipping the step; the best sunscreen is the one you will actually wear every day.
Everyday habits that help
Sunscreen works best alongside simple habits rather than on its own. Shade, a hat and covering clothing all reduce how much sun reaches your skin, so the sunscreen has less to do. Remember the spots people miss: ears, the back of the neck, the tops of the feet and the hairline. Keep a product you actually like somewhere you will reach for it, by the door or in a bag, since the one you remember to use beats the one left in a drawer.
Storage and shelf life
Sunscreen has a limited life, and heat degrades it, so a tube left in a hot car all summer may not perform as expected. Check the expiry date, note any mark showing how long it lasts once opened, and replace it when it is old. Protection you can rely on depends on a product that is still in good condition.
What this page is not
This is general information, not medical or dermatological advice, and it avoids specific SPF recommendations because sun strength, skin and local guidance all differ. For how much protection you personally need, follow local health guidance and ask a professional.
Last checked 2026-11-10