What Does the SPF Number Mean?

Today, we will explore something important for keeping your skin safe and healthy: SPF! Whether you’re heading to the beach, running errands, or just enjoying a sunny day outside, knowing about sunscreen can help protect your skin from UV radiation.

It’s not just about avoiding sunburn — SPF plays a key role in preventing premature aging and reducing your risk of skin cancer. Let’s get started.

What Is SPF?

SPF stands for sun protection factor, and it’s one of the most important tools for protecting your skin. It measures how well a sunscreen can shield your skin from the sun’s harmful ultraviolet (UV) rays, more specifically UVB rays. This kind of UV exposure is responsible for sunburn and can contribute to skin cancer.

Studies show that even wearing SPF 15 daily can reduce your risk of squamous cell carcinoma by 40% and melanoma — the deadliest type of skin cancer — by 50% (1).

Regular use of sunscreen also prevents premature aging, such as wrinkles, dark spots, and loss of skin elasticity. For the best protection, always choose a broad-spectrum sunscreen, which protects against both UVB and UVA rays. UVA rays can penetrate deeper into the skin, causing long-term damage and aging, even if you don’t feel a burn.

Sunscreen isn’t just for sunny days, either — it’s an everyday essential!

What Does the SPF Number Indicate?

The SPF number shows how long you can stay in the sun without getting a sunburn. For example, if you normally burn after 10 minutes in the sun, an SPF 30 sunscreen should protect you for about 30 times longer — about 300 minutes!

But remember, no sunscreen can block 100% of the sun’s rays, so it’s still important to reapply. Board-certified dermatologist Jeremy Brauer, M.D., says, “The higher the SPF, the better” (2).

How Does Sunscreen Work?

Sunscreen works in two main ways:

Chemical Sunscreens

Chemical sunscreens work to prevent skin damage by absorbing harmful rays and converting them into heat, which is then released from the skin. These sunscreens contain active ingredients like avobenzone, oxybenzone, and octinoxate. They are often lightweight, easy to apply, and blend seamlessly into the skin, making them a popular choice for daily use. However, they may cause irritation for people with sensitive skin or conditions like rosacea.

Physical (or Mineral) Sunscreens

Physical sunscreens act like a shield on your skin, reflecting and scattering the sun’s UV rays before they can penetrate. They use natural minerals like titanium dioxide and zinc oxide as active ingredients. These sunscreens are great for sensitive skin since they’re less likely to cause irritation.

They also start working immediately after application, unlike chemical sunscreens, which need about 15-30 minutes to activate. However, physical sunscreens can sometimes leave a white cast, especially on darker skin tones.

What Type of Sunscreen Is Best?

The best sunscreen is the one you will actually use! “Even if it’s not the perfect sunscreen,” says dermatologist Anish Patel, “it’s better to wear something rather than nothing” (3).

Look for a broad-spectrum sunscreen with at least SPF 30 for a sufficient level of protection from both UVA and UVB radiation. It should also be water-resistant if you’re swimming or sweating. You can choose between chemical and physical sunscreens based on your skin type and personal preference.

What Are Signs of Sun-Damaged Skin?

Sun damage doesn’t just happen after a single sunburn — it builds up over time and can show up in different ways. By recognizing these signs early, you can prevent further sun damage and maintain healthier, more youthful-looking skin.

Here’s a closer look at the common signs of sun-damaged skin and how they affect you:

Dark Spots

Dark spots, also called hyperpigmentation or sunspots, are areas where the skin produces extra pigment due to UV exposure. These spots can range in color from light brown to dark brown and are most noticeable in areas frequently exposed to the sun, like your face, hands, shoulders, and arms.

“Sunspots, spots with textures, actinic keratosis, seborrheic keratosis, these little keratoses on the skin are something that, as we age, we don’t really like when we look in the mirror,” says licensed aesthetician and laser specialist Erin Blackwell (4). While they’re not harmful, they can make your skin tone look uneven.

Redness and Irritation

Prolonged sun exposure can cause your skin to turn red, inflamed, and sensitive to the touch. This redness isn’t just sunburn — it can also indicate broken capillaries or long-term irritation from the sun’s rays.

Repeated exposure without protection can lead to more serious skin issues over time, such as chronic inflammation or rosacea.

“Reducing the inflammation caused by UV exposure can really help to reduce flare-ups in rosacea patients. And remember to reapply every two hours or more frequently if sweating, swimming, or toweling off,” explains board-certified dermatologist Joel Cohen, M.D. (5).

Dullness

The sun’s UV rays can damage your skin’s outer layer, causing it to lose its natural glow. Over time, this leads to a dull, rough texture that feels dry and looks tired. This dullness can happen even if you don’t experience visible sunburn, as UV damage can weaken the skin’s ability to retain moisture and reflect light.

“UV rays damage and kill skin cellsleading to sunburn, blisters, dry, dull and uneven skin tone, pigmentation and a major loss of collagen,” says cosmetic dermatologist Dr Chytra Anand (6).

Wrinkles

“When it comes to wrinkles, there are other much more impactful factors than genetics at play. For instance, up to 90 percent of visible skin changes are a result of damage from the sun, called photodamage,” explains Ivona Percec, M.D. (7).

UV rays break down collagen and elastin in your skin — two proteins that keep it firm and smooth. When these proteins are damaged, the skin loses its elasticity, leading to fine lines, sagging, and wrinkles. Crow’s feet around the eyes and deep lines on the forehead or around the mouth are common signs of sun-induced aging.

How To Prevent Sun Damage

Protecting your skin from the sun is one of the most important things you can do to maintain its health and appearance.

Here’s a deeper dive into each prevention tip:

Use Sunscreen, Even on Cloudy Days

Many people think sunscreen is only necessary on sunny days, but this isn’t true. Up to 80% of the sun’s UV rays can penetrate clouds, meaning your skin is still at risk even when it’s overcast.

“Prolonged UVA exposure damages the collagen fibers in the [skin],” explains Lortscher. “It’s not just long days on the beach causing visible aging. UVA exposure happens every time you walk to the car, work outside on cloudy days, or even sit by a window,” says board-certified dermatologist Dr. David Lortscher (8).

To protect yourself, apply a broad-spectrum sunscreen with an SPF rating of at least 30 every morning and reapply every two hours if you’re outside or sweating. Don’t forget often-missed spots like your ears, neck, and the tops of your feet!

Incorporate Antioxidant Skincare

Antioxidants, such as vitamins C and E, are powerful tools in your skincare routine. These ingredients help support your skin during exposure to free radicals, which are unstable molecules caused by UV exposure that can damage your skin cells.

Using a serum or moisturizer with antioxidants under your sunscreen provides an extra layer of defense, helping to prevent premature aging and potentially minimize the effects of sun damage.

Wear Protective Clothing

Clothing is your first physical barrier against the sun. When spending time outdoors, opt for long-sleeved shirts, wide-brimmed hats, and UV-blocking sunglasses.

Many clothing brands now offer garments with built-in UV protection for added convenience. Lightweight, breathable fabrics like cotton or linen can keep you cool while shielding your skin. Don’t forget to wear gloves if you’ll be outside for extended periods, especially if your hands are exposed to the sun.

Stay Hydrated

Hydration is key to maintaining your skin’s natural barrier and resilience. When you’re dehydrated, your skin can become dry, dull, and more prone to sun damage.

Aim to drink plenty of water throughout the day, especially if you’ve been sweating or spending time in the sun. Eating water-rich foods like fruits and vegetables also helps keep your skin hydrated and glowing.

The Bottom Line

By combining these tips with a consistent skincare routine, you can protect your skin from sun damage and enjoy healthy, radiant skin for years to come. Prevention is easier than trying to undo the damage later, so start these habits today!

Taking care of your skin is important, and using sunscreen is one of the best ways to do it. It’s a simple step that makes a big difference in keeping your skin healthy, youthful, and glowing.

Remember to choose a broad-spectrum sunscreen with at least SPF 30, apply it daily, and follow the tips to protect your skin. Don’t forget — your future self will thank you! Stay safe in the sun, everyone.

Sources:

1. The efficacy and safety of sunscreen use for the prevention of skin cancer | PMC (nih.gov)

2. How Much SPF Do You Need? Here’s Everything You Need to Know About Sunscreen, According to Dermatologists | GQ

3. Is mineral sunscreen better than chemical sunscreen? | MD Anderson Cancer Center

4. Expert Tips On Battling Sun Damage For Healthy Skin | Weather.com

5. The 16 Best Sunscreens for Rosacea, According to a Derm | Who What Wear UK

6. Here’s how sun damage shows up on dry, oily and sensitive skin types | Vogue India

7. The Truth About Wrinkles: 5 Common Wrinkle Myths Debunked | Penn Medicine

8. An Essential Checklist to Reversing Sun Damage and Dark Spots | Healthline