SPF 30 or SPF 50: which should I use?

Is SPF 50 much better than SPF 30?

SPF means sun protection factor and measures protection primarily against UVB, the rays chiefly responsible for sunburn. SPF 50 offers more protection than SPF 30, but the percentage difference is small, which makes sunscreen shopping less like a high score contest. Those percentages assume enough sunscreen is applied; a thin layer will not deliver the protection printed on the bottle.3

UVA contributes to skin ageing and skin cancer, so SPF is not the whole shopping checklist. In the UK, look for SPF 30 or higher with a four or five star UVA rating. Check the expiry date too.345

Does SPF 50 last longer than SPF 30?

No. Higher SPF lasts the same amount of time as lower SPF. Reapply either approximately every two hours outdoors and after swimming or sweating. Reapply after towel drying too. Water resistant sunscreen still needs reapplication; no sunscreen is waterproof or sweatproof.15

Is SPF 30 enough for everyday use?

Yes. Broad spectrum, water resistant SPF 30 meets the recommended minimum for everyday outdoor use. Apply sunscreen on exposed skin every day you will be outside, including cloudy days. UV damage is not reserved for hot weather: exposure also contributes to premature ageing, dark patches and skin cancer.15

Choose a formula you will use consistently, provided it meets those protection requirements. How a sunscreen feels and rubs in matters because an unpleasant formula is harder to keep using, which is a lot of influence for something that never gets a number on the label. Texture deserves a vote in the purchase, not permission to overrule the protection label.16

How to use either SPF properly

1. 1Apply sunscreen to dry skin 15 minutes before going outdoors.
2. 2Use enough to cover exposed skin generously. Most adults need about one ounce, roughly a shot glass, for exposed body skin; larger bodies can need more. For your face, use at least one teaspoon.
3. 3Cover every exposed area, including your neck, ears, the backs of your arms and the tops of your feet. Use a wide brimmed hat to protect a scalp with little hair.
4. 4Reapply about every two hours while outdoors, and after swimming, sweating or towel drying.

Add shade and clothing rather than relying on sunscreen alone. Closely woven clothing, long sleeves, a wide brimmed hat and sunglasses provide additional protection. No sunscreen filters every UV ray, so even a carefully applied SPF 50 cannot do the entire job.47

When the choice needs more care

For sensitive skin, consider a mineral sunscreen containing zinc oxide, titanium dioxide or both. Sensitive skin changes the formula to consider, not the need for SPF 30 or higher.1

If you have lupus affecting your skin, daily sun protection is especially important because UV exposure can trigger flares. Use broad spectrum, water resistant SPF 30 or higher alongside shade and protective clothing. Ask your doctor whether any medication you take increases light sensitivity.7

After skin cancer, keep protecting your skin: new UV damage can lead to new cancers. Follow your dermatologist's schedule for skin checks, and report new or changing moles or unusual spots to your doctor.45