In short
- Use a broad-spectrum sunscreen with SPF 30 or higher every day. SPF measures UVB protection; broad-spectrum, PA or UVA labels cover UVA.
- Most people apply too little. For the face and neck, use about a quarter teaspoon, or two finger lengths.
- Reapply every two hours outdoors, and after swimming, sweating or towel drying.
- The best sunscreen is the one you'll wear every day. Mineral and chemical filters both work.
If you only use one skincare product, make it sunscreen. It’s the most effective way to prevent dark spots, visible aging and skin cancer, and it protects the results of every other product in your routine. Yet most people choose it poorly, apply too little, and forget to reapply.
This is the guide to getting it right.
UVA, UVB and visible light
Sunlight reaching the skin includes:
- UVB: the main cause of sunburn and a major cause of skin cancer. Stronger in summer and at midday.
- UVA: penetrates deeper, drives photoaging (wrinkles, loss of firmness) and pigmentation, and contributes to skin cancer. Present all year and passes through clouds and window glass.
- Visible light (especially high-energy blue-violet light): can worsen hyperpigmentation and melasma, particularly in medium to deep skin tones.
Reading a sunscreen label
SPF (Sun Protection Factor)
SPF measures protection against UVB. In lab testing, at the standard amount (2 mg per square centimeter of skin):
| SPF | UVB filtered (approximately) |
|---|---|
| 15 | 93% |
| 30 | 97% |
| 50 | 98% |
| 100 | 99% |
SPF doesn’t scale linearly, but in real life people apply a fraction of the tested amount, so a higher SPF provides a useful safety margin.
Broad spectrum, UVA and PA
SPF alone says nothing about UVA. Look for:
- “Broad spectrum” (US): UVA protection proportional to SPF.
- UVA in a circle (EU): UVA protection is at least one third of the SPF.
- PA+ to PA++++ (Asia): UVA protection grade; more plus signs mean more protection.
- Boots star rating (UK): one to five stars for UVA.
Water resistance
“Water resistant” (40 minutes) or “very water resistant” (80 minutes) means the SPF holds for that long while swimming or sweating. Reapply after.
Mineral vs. chemical filters
| Mineral (physical) | Chemical (organic) | |
|---|---|---|
| Filters | Zinc oxide, titanium dioxide | Avobenzone, octocrylene, newer filters such as bemotrizinol and bisoctrizole |
| How they work | Mostly absorb UV, plus some reflection | Absorb UV |
| Pros | Often better tolerated by sensitive skin; zinc oxide covers UVA well | Light, invisible textures; easier to apply generously |
| Cons | Can leave a white cast on deeper skin (less so when tinted) | Some filters can sting sensitive eyes or skin |
Both types protect well. Choose by texture, tolerance and finish, because the sunscreen you like is the one you’ll wear every day. Sensitive skin often prefers mineral; deeper skin tones often prefer modern chemical or tinted mineral formulas.
How much sunscreen to apply
The SPF on the label is measured at 2 mg/cm². For an adult face and neck, that’s roughly:
- A quarter teaspoon (about 1.25 ml), or
- Two finger lengths: two strips along your index and middle finger.
Most people use half that or less, which means they get a fraction of the stated protection.
How to apply
- Last step of your morning skincare, after moisturizer. See routine order.
- Don’t forget ears, neck, the hairline, around the eyes and the back of the neck.
- Wait a few minutes before makeup.
- Reapply every two hours outdoors, and after swimming, sweating or towelling off.
- Lips: use a lip balm with SPF.
Reapplying over makeup
- SPF sprays or mists designed for the face, applied generously.
- SPF powders or cushion compacts, as a top-up.
- Stick sunscreens for touch-ups on the go.
These are less precise than a full layer, but much better than nothing.
Choosing by skin type
- Oily or acne-prone: fluid, gel or matte formulas, non-comedogenic.
- Dry: creamy, moisturizing formulas.
- Sensitive: fragrance-free, often mineral.
- Deep skin tones: tinted mineral or sheer chemical formulas without white cast; tinted iron oxide formulas help against visible light.
- Pigmentation or melasma: SPF 50, broad spectrum, tinted. See our dark spots guide.
Sunscreen myths
- “I don’t need it on cloudy days.” Much of the UV passes through clouds.
- “My moisturizer has SPF 15, that’s enough.” It’s below the minimum most dermatologists recommend, and you probably don’t apply enough.
- “Darker skin doesn’t need sunscreen.” It does, for skin cancer prevention and especially for pigmentation.
- “Sunscreen causes vitamin D deficiency.” Studies of real-life use haven’t shown that typical sunscreen use causes deficiency. Ask your doctor about vitamin D if you’re concerned.
- “Higher SPF lets me stay out longer.” Reapply every two hours regardless.
Sunscreen and your other products
Sunscreen is what makes active ingredients worth using:
- Retinoids and AHAs can make skin more sun-sensitive.
- Brightening ingredients can’t keep up with daily UV.
- Vitamin C under sunscreen gives extra antioxidant protection.
Any realistic timeline for fading dark spots or softening fine lines, including a 90-day skincare simulation, assumes you protect your skin every day. Without sunscreen, progress stalls. See how long skincare takes to work.
The bottom line
Broad spectrum, SPF 30 or more, two finger lengths, every morning, reapplied every two hours outdoors. Choose a texture you love, and it becomes the easiest, most effective step in your routine. Living somewhere hot and sunny? Read skincare for hot, sunny climates.
Frequently asked questions
Is SPF 50 much better than SPF 30?
In lab conditions, SPF 30 filters about 97% of UVB rays and SPF 50 about 98%. The difference matters more in real life because people under-apply: a higher SPF gives a margin. SPF 30 is a minimum; SPF 50 is a good choice for fair skin, strong sun or pigmentation concerns.
Do I need sunscreen indoors or on cloudy days?
On cloudy days, yes: a large share of UV passes through clouds. Indoors, UVA can pass through windows, so if you sit near a window for long periods or have pigmentation concerns, wearing sunscreen is sensible.
Does makeup with SPF count as sunscreen?
Rarely on its own, because you'd need to apply far more foundation or powder than people normally do to reach the labelled SPF. Wear a sunscreen underneath, and use SPF makeup or powder as a top-up.
Does darker skin need sunscreen?
Yes. Melanin offers some natural protection, but darker skin can still burn, develop skin cancer and, especially, develop hyperpigmentation and melasma, which UV and visible light worsen. Tinted sunscreens blend well and help with visible light.
This article is for general information only and is not medical advice. Skin is individual: for a skin condition, a reaction or anything that worries you, please see a dermatologist or doctor.
