Knowing how to choose sunscreen starts with three things on the label: broad-spectrum, SPF 30 or higher, and a finish you will actually wear every day. Everything else, including whether you pick a mineral or chemical formula and whether you care about a PA rating, comes down to your skin, your climate and how you spend your day. The best sunscreen is the one you apply generously and reapply on time.
That sounds simple until you stand in a shop or scroll an online listing and see SPF 15, 30, 50, 50+, PA+++, “reef safe”, “physical”, “hybrid” and “clean”. This guide on how to choose sunscreen explains what each term really means, how to match a formula to your skin, and how to avoid the mistakes that matter more than the label.
Key Takeaways
- Choose a product labelled “broad-spectrum” with SPF 30 or higher, as dermatologists at the American Academy of Dermatology (AAD) suggest.
- SPF mostly describes UVB (burning) protection. A PA rating, common on Asian-market products, describes UVA (ageing and pigment) protection.
- Mineral sunscreens use zinc oxide or titanium dioxide; chemical sunscreens use organic filters that absorb UV. Both can protect well when used properly.
- Most people apply far less than the amount used in lab testing, so the real-life SPF is lower than the number on the bottle.
- Reapply about every two hours outdoors, and after swimming or heavy sweating.
- Sunscreen is one layer of sun protection, not a replacement for shade, clothing and a hat.
What SPF Tells You When You Choose Sunscreen
SPF stands for sun protection factor. It measures how well a product shields skin from UVB rays, the wavelengths that cause sunburn. In lab testing, SPF compares how long skin takes to redden with and without product.
The scale is not linear, which surprises many people. Commonly cited figures say SPF 15 filters roughly 93% of UVB, SPF 30 about 97%, and SPF 50 about 98%. Going from 30 to 50 adds only a small increase in filtering, which is why the extra number is less important than applying enough.
The AAD recommends SPF 30 or higher. If you burn easily, live near the equator, spend long periods outdoors or have a history of sun damage, a higher number gives a little more margin. For a daily commute and office work, SPF 30 applied properly beats SPF 100 applied thinly.
Why the number on the bottle overstates real-life protection
Labs test sunscreen at a thick, even layer of 2 mg per square centimetre. In everyday life, most people put on roughly a quarter to half of that. A rough rule many dermatology sources use for the face and neck is about a quarter of a teaspoon, though body size and product texture vary. If the bottle says SPF 50 but you apply a thin smear, you may get protection closer to SPF 10 to 15.
A practical way to check yourself: if a bottle that should last a week of daily face use is lasting a month, you are almost certainly under-applying.
Broad-Spectrum and the PA Rating: Covering UVA
UVA rays penetrate deeper than UVB. They contribute to wrinkles, loss of firmness, and pigment changes, and they pass through window glass. SPF does not describe UVA protection, so a separate signal is needed.
In the United States, “broad-spectrum” is that signal. It means the product passed a test showing it protects across both UVB and UVA ranges. In Europe, a UVA logo (the letters “UVA” in a circle) shows that UVA protection is at least one third of the stated SPF. In Japan, Korea and many Asian markets, you will see a PA rating.
| Rating | What it generally means | When it matters |
|---|---|---|
| PA+ | Some UVA protection | Short, low-intensity exposure |
| PA++ | Moderate UVA protection | Everyday errands |
| PA+++ | High UVA protection | Daily wear for most people |
| PA++++ | Highest tier of UVA protection | Long outdoor days, pigment-prone skin |
The PA scale is based on a lab measurement called persistent pigment darkening. Because it was designed around skin pigmentation, it is especially relevant if you tend to develop dark marks or have melasma. If your sunscreen carries a PA label, aim for PA+++ or PA++++. If it does not, “broad-spectrum” in the US or the UVA circle in Europe and the UK is your guide.
Mineral vs Chemical Sunscreen: How They Differ
The old shorthand says mineral sunscreens “reflect” light and chemical ones “absorb” it. That is a useful simplification, though modern research suggests mineral filters also absorb a share of UV. What matters in practice is how each type feels, looks and behaves on your skin.
Mineral (inorganic) sunscreens use zinc oxide, titanium dioxide, or both. They sit on the surface of skin and work immediately after application. Chemical (organic) sunscreens use filters such as avobenzone, octocrylene or newer-generation filters. They are absorbed into the upper layer of skin and need a short time to set before sun exposure, usually about 15 minutes according to label directions.
| Feature | Mineral | Chemical |
|---|---|---|
| Main filters | Zinc oxide, titanium dioxide | Avobenzone, octocrylene, and others |
| Feel on skin | Can feel thicker, may leave a white cast | Usually lightweight and sheer |
| Works right away? | Yes | Needs a short wait, per label |
| Sensitive or reactive skin | Often better tolerated | Some people sting or react |
| Darker skin tones | White cast is more visible unless tinted | Rarely leaves a cast |
| Under makeup | Can pill or look heavy | Usually layers smoothly |
| Price range | Varies widely, similar to chemical | Varies widely |
A note on safety questions
You may have seen headlines about chemical filters absorbing into the bloodstream. The US Food and Drug Administration has said zinc oxide and titanium dioxide are generally recognised as safe and effective, and has asked for more safety data on several organic filters. That is a request for more research, not a finding that those products are harmful, and the agency has continued to say sunscreen should be used. Nothing in the current evidence suggests skipping sunscreen is the safer choice. If a particular filter worries you, a mineral formula is a reasonable alternative.
How to Choose Sunscreen for Your Skin Type
Once you have the basics of how to choose sunscreen, texture is where most people succeed or fail. A sunscreen you dislike ends up in a drawer.
Oily or acne-prone skin
Look for gels, fluids or lightweight lotions labelled non-comedogenic. Mattifying finishes are common. If you are building an oil-control routine, see our guide to a skincare routine for oily, acne-prone skin for where sunscreen fits.
Dry or mature skin
Cream textures that include glycerin, ceramides or hyaluronic acid double as moisturiser. If your skin often feels tight or flaky, the advice on fixing dry, flaky skin may help you decide whether to layer a separate moisturiser first.
Sensitive or reactive skin
Fragrance-free mineral formulas with few ingredients are a sensible starting point. Patch test on your inner forearm or behind the ear for a few days before using on your face.
Darker skin tones
Sunscreen matters for all skin tones, because sun exposure can deepen dark marks and trigger pigment conditions even where sunburn is less visible. Tinted mineral formulas that include iron oxides reduce white cast and add protection against visible light, which AAD guidance mentions for melasma. Chemical gels are another route if you prefer something sheer.
If you have hyperpigmentation
Daily sunscreen is the foundation of any pigment plan; creams and serums are far less effective if sun exposure keeps restarting the process. Our overview of hyperpigmentation and dark spots explains why.
Water Resistance, Sport and Sprays
No sunscreen is waterproof or sweatproof. US labelling only allows “water resistant,” paired with 40 or 80 minutes. That is how long the stated SPF holds up in water before you need to reapply. Towel drying removes product, so reapply afterwards regardless of the time.
Sprays and powders are convenient for reapplying over makeup or on the scalp parting, but it is hard to judge how much you have put on. Spray into your hands first for the face to avoid inhaling mist, and rub in until you see an even sheen. Stick formats work well for the lips and around the eyes.
How to Apply and Reapply
- Apply as the last step of skincare and before makeup. Moisturiser first, then sunscreen, as outlined in our guide to a morning and night skincare routine.
- Use enough. Many people prefer the “two-finger” method: squeeze a line of product along the length of your index and middle fingers and apply it to the face and neck.
- Do not forget the edges. Ears, hairline, the back of the neck, eyelids, and tops of the hands are common missed spots.
- Wait for chemical formulas to set if the label asks you to.
- Reapply about every two hours during extended outdoor time, and straight after swimming, towel drying or heavy sweating.
If you wear makeup and work indoors, reapplication is realistic to manage at lunch only if you are near a window or going outside. A powder or stick sunscreen can make this easier. Do not expect SPF in foundation to be enough on its own, since you would need to apply a very thick layer to reach the labelled number.
How to Choose Sunscreen Wisely: Mistakes That Matter More Than the Label
- Skipping cloudy days. A large share of UV passes through cloud cover.
- Using an expired bottle. Check the date; heat, such as a hot car, can degrade filters. If the texture has separated or smells off, replace it.
- Relying on sunscreen alone. Shade, tightly woven clothing, a wide-brim hat and sunglasses reduce how much sunscreen has to do.
- Applying only to the face. The neck, chest and hands show sun damage early.
- Saving it for summer. UVA levels remain fairly constant through the year in many regions.
A Simple Decision Guide for Choosing Sunscreen
| Your situation | A sensible starting point |
|---|---|
| Office worker, mostly indoors | Broad-spectrum SPF 30, lightweight lotion or gel |
| Beach day or hiking | Broad-spectrum SPF 50, water resistant 80 minutes, plus hat and shade |
| Sensitive skin that stings easily | Fragrance-free mineral formula, patch tested |
| Melasma or dark marks | Tinted mineral with iron oxides, PA+++ or higher if available |
| Oily, acne-prone skin | Oil-free gel or fluid labelled non-comedogenic |
| Children and babies | Ask a paediatrician; babies under six months should be kept out of direct sun |
Frequently Asked Questions
Is SPF 50 much better than SPF 30?
Only slightly. SPF 30 filters about 97% of UVB and SPF 50 about 98%. Applying enough and reapplying matter more than the higher number.
Do I need sunscreen indoors?
If you sit near a window for long periods, UVA can pass through glass, so a daily sunscreen is reasonable. If you spend the day in the middle of a windowless building, you need much less.
Is mineral sunscreen safer than chemical?
Both are regulated and widely used. Mineral filters have the strongest safety record in current US regulatory reviews, and they suit reactive skin, but a well-tolerated chemical sunscreen that you wear daily is better than a mineral one you skip.
Can I use last year’s sunscreen?
Check the expiry date. Products without one are generally considered good for about three years if stored away from heat. Throw it out if the texture or smell has changed.
What does PA++++ mean?
It is the top tier of a UVA protection scale used mainly in Japan, Korea and other Asian markets. It suggests a high level of defence against UVA rays.
Should I wear sunscreen under makeup?
Yes. Apply sunscreen after moisturiser and give it a minute or two before foundation. Treat makeup SPF as a bonus, not your main protection.
Does sunscreen cause vitamin D deficiency?
Real-life use does not seem to cause deficiency for most people, since few apply enough to block all UV. If you are concerned about your level, ask your doctor about a blood test rather than skipping sunscreen. Safer options, such as food sources and doctor-guided supplements, exist.
How much sunscreen does the body need?
A common guideline is about a shot-glass amount (roughly 30 ml, or one ounce) for the exposed body. Use more if you are in a swimsuit.
The Bottom Line
The simplest answer on how to choose sunscreen, whether for daily errands or a beach trip, is to start with broad-spectrum and SPF 30 or higher, then choose the texture and type that suit your skin so you will use it every day. Add a PA rating check if the product has one, and consider a tinted mineral formula if pigment is a concern. Then focus on technique: apply generously, cover the spots people forget, and reapply every two hours outdoors. A mid-priced sunscreen used properly will outperform an expensive one used sparingly.
This article is for general informational purposes only and does not replace advice from a qualified healthcare professional. Individual needs differ, and costs, rules and guidelines change — please check with a doctor, pharmacist, or the relevant official source for guidance specific to your situation.
