You can spend a fortune on serums, retinol, and peptides — but skip sunscreen, and you are undoing most of that work every single day. UV exposure is the single biggest driver of visible ageing and the one variable almost entirely within your control. Here is what actually matters when choosing one.
Why SPF Matters More Than Any Other Product
Up to 90% of visible skin ageing — fine lines, sagging, dark spots, uneven tone — is caused by cumulative UV exposure, not the natural passage of time. Every ingredient discussed on this site, from retinol to vitamin C to peptides, works to repair or prevent damage that sunscreen could have stopped from happening in the first place.
Chemical vs Mineral Sunscreen
- Chemical (organic) filters — ingredients like avobenzone and octocrylene absorb UV rays and convert them to heat. They tend to feel lighter and blend in more easily, but can irritate sensitive or acne-prone skin.
- Mineral (physical) filters — zinc oxide and titanium dioxide sit on top of skin and physically reflect UV rays. Better tolerated by sensitive skin and safer for reactive or post-procedure skin, though older formulas can leave a white cast.
- Hybrid formulas — many modern sunscreens combine both types to balance cosmetic elegance with broad protection.
What SPF Number Actually Means
SPF measures protection against UVB rays specifically — the type that causes sunburn. SPF 30 blocks about 97% of UVB rays; SPF 50 blocks about 98%. The jump from 30 to 50 is smaller than it sounds, but every percentage matters over years of daily use. Always look for broad spectrum on the label, which confirms UVA protection as well — UVA rays are the ones responsible for deep, long-term ageing damage.
How Much to Apply (and How Often)
Most people apply far too little. For the face and neck alone, you need roughly a quarter-teaspoon — about two finger-lengths’ worth. Reapply every two hours if you are outdoors, and always reapply after swimming or heavy sweating. On an average indoor day, one thorough morning application is generally sufficient.
Do you need SPF indoors? If you are near a window, yes — UVA rays penetrate glass. If you are working from a well-lit room with no direct window exposure, the daily necessity is lower, but most dermatologists still recommend making SPF a non-negotiable final step of every morning routine regardless.
Layering SPF with Your Routine
Sunscreen should always be the last step of your morning routine, applied after moisturiser and before makeup. Give it a minute or two to set before applying anything on top. If you are using vitamin C in the morning, apply it before sunscreen — the antioxidant protection and the SPF barrier work together rather than against each other.
Top Sunscreen Picks
La Roche-Posay Anthelios Melt-in Milk is a dermatologist favourite for its lightweight, non-greasy finish. EltaMD UV Clear is a cult favourite for acne-prone and sensitive skin thanks to its niacinamide content. For a mineral option without the white cast, Supergoop Unseen Sunscreen has become one of the most talked-about launches in recent years.