Why SPF 100 Isn't Necessarily Better

Why SPF 100 Is Not Always Better: Debunking Sunscreen Myths

You may have also pondered while you were at it: “With sunscreen, should I shell out for SPF 100 to ensure the best protection?” You're not alone. That larger number sounds safer, right? When you need to take your skin from coach to first class.

But here’s the thing: The distinction between SPF 30 and SPF 100 isn’t actually what you’d imagine. How to apply sunscreen properly is far more important than chasing triple-digit SPF numbers on the bottle.

The truth behind high-SPF sunscreens might surprise you—a bit, at least—and change everything you thought you knew about keeping your skin safe this summer.

SPF: What You Need To Know – In More Depth

The Science Behind SPF Numbers

Have you ever really known what means that number following SPF on your sunblock bottle? Not as gnarly as you might expect. SPF means Sun Protection Factor, and it only measures protection against UVB rays -– the rays that cause sunburn. If you see SPF 30, it theoretically means the sunscreen can provide sunburn protection for 30 times longer than if you didn’t have it on.

Here’s the simple math: If your unprotected skin starts to burn after 10 minutes in the sun, an SPF 30 would protect you for 300 minutes (5 hours). But don’t get too excited — this is in a perfect laboratory setting, not in your real life at the beach when you are swimming and sweating.

What SPF 30, 50, and 100 Really Mean?

The SPF game becomes even murkier when you consider the actual percentage of UVB rays blocked:

Notice something? And the leap from SPF 30 to 100 gets you only 2% more protection! You’re already gaining great protection at SPF 30, and the increases become relatively negligible as you go up.

Diminishing Returns: Why Higher Isn't Always Better

That expensive SPF 100 sunscreen? It’s giving you barely more protection than SPF 50. But the protection boost follows a curve that flattens steeply after SPF 30.

The other problem is that ultra-high SPF products can lead to a false sense of security. So you may be thinking, “I have on SPF 100 — I’m basically invincible!” and end up not reapplying or staying out for too long. The truth? You still have to reapply every two hours no matter what the SPF number you choose.

And higher SPF formulas often feel heavier on your skin. “You’re not going to put on enough of a thick SPF 100 product if you hate that greasy feeling.”

The "Two Percent Problem" in High SPF Sunscreens

This gets us to what dermatologists refer to as the “2% issue.” There’s only a 1% difference between SPF 50 and SPF 100 (98% vs. 99%) protection, but manufacturers price accordingly for that fraction of extra protection you get.

Another issue? High-SPF sunscreens can even offer UVA protection levels lower than you might expect. Because, even though SPF shows how much UVB (burning) rays are blocked, UVA (aging) rays are equally harmful as they can penetrate more deeply into the skin, leading to premature aging and an increased likelihood of skin cancer. The subject of high-SPF products that deliver abundant UVB protection, but insufficient UVA protection, has been covered at length.

Your best bet? Opt for a broad-spectrum SPF 30-50 sunscreen that you don’t hate rubbing on, so that you’ll actually use it generously and reapply frequently. It’s not a question of most versus fewest — it is a matter of applying sunscreen properly.

High SPF = No Need to Reapply Sunscreen?

A The False Sense of Security Myth

Feeling indestructible in that SPF 100 slathered on? Think again. A big misconception about high SPF products is that they render you bulletproof against the sun. When you reach for SPF 100, you may think you can spend all day outside without a worry. This false confidence can result in more sun damage than if you’d applied a lower SPF properly.

Here’s the reality: SPF 50 blocks roughly 98% of UVB rays; SPF 100 blocks about 99%. That's just a 1% difference! But research indicates that users of higher SPF sunscreens tend to stay in the sun longer, and are less likely to use protective measures such as seeking shade or wearing sun protective clothing.

B. Application Amount Reality

Ever squeezed out a pea-sized amount of sunscreen for your entire face? You're not alone, but you're also not protected. The reality is that most people apply only 25-50% of the recommended amount of sunscreen, regardless of the SPF number on the bottle.
For proper protection, you need to apply about 1 ounce (a shot glass full) of sunscreen for your entire body. When you skimp on application, your actual protection drops dramatically. That SPF 100 you're relying on might only be giving you SPF 10 protection if you're applying too little.
Consider this: a thick, even layer of SPF 30 applied properly offers better protection than a thin layer of SPF 100.

C. Reapplication Requirements Regardless of SPF Factor

Got SPF 100? Great. But if you put it on at 8 a.m. and now it’s noon, you are basically unprotected.” But remember every sunscreen is going to break down on your skin no matter how high the SPF, and one application will not protect you for a full day.

You should reapply every two hours, or immediately after swimming or sweating — no matter what SPF the stuff boasts. The molecules in sunscreen that shield your skin deteriorate from sun exposure — that initial protection doesn’t last all day.

If you’re thinking, “But I slathered on SPF 100 this morning!” getting sunburned at 3 PM you’ve been a victim of this common misunderstanding.

D. Protection Duration Fallacies

You know how SPF 100 is supposed to last twice as long as SPF 50? Total myth. The SPF measure doesn’t let you know how long you’re protected; it tells you how much time you have protected from UVB rays (those are the ones that cause a sunburn).

Keep in mind, ALL sunscreens, regardless of SPF, need to be reapplied every two hours. The number doesn’t determine time — it’s about strength of protection, not length.

E. Cost of the Benefit for Higher SPF Product

Is that extra $10 worth it for SPF 100? The math works out badly for high-SPF products when you compare the cost to the benefits.

20 - 50% more expensive for higher SPF products are 20-50% more expensive than moderate SPF products. But that extra protection is marginal — that 1% of difference between SPF 50 and SPF 100 is rarely worth the price hike.

Your money may be better spent on a good SPF 30 to 50 product that you will apply generously and frequently. Or maybe invest in UV-protective clothing and wide-brimmed hats, which give you constant coverage without reapplication.

Smart Sunscreen Selection Strategies

Skin Type Considerations

Your skin is unique, and so is the sunscreen that protects it. If you’re acne-prone, opt for oil-free or noncomedogenic, and avoid anything that will clog your pores. Got sensitive skin? Steer clear of products that contain fragrances, preservatives like parabens, or oxybenzone—these irritants are so widespread and are likely to leave you red and angry.

Dry skin will benefit from water-based sunscreens with hydrating components, such as hyaluronic acid or ceramides in cream form. They will protect and add moisture. If you’re oily, what you want instead are lightweight, mattifying gel formulas that don’t turn you into an oil slick by noon.

And here’s what too many folks overlook: Darker skin tones also require protection from the sun! Though melanin provides some natural protection, it’s not sufficient. Opt for tinted sunscreens, or a product specially made to meld without leaving that ghost face.

Activity-Based Protection Needs

Playing beach volleyball all day? Sitting in an office? Let your actions guide your sunscreen selection.

For intense outdoor activities/water sports you want:

• Water-resistant formulas (40-80 minutes of protection while swimming)
• Higher SPF (at least 30-50)
• More frequent reapplication (every 2 hours minimum)
• For daily errands or office work:
• Lighter formulations that work well under makeup
• Products with added antioxidants to fight urban pollution
• At least SPF 30

Runners and heavy sweaters, stick formulations for faces — they stay put better when you’re dripping. Mineral-based options that are less likely to sting the eyes when sweating could be favored by hikers.

Products to use daily vs Products for the beach day

Your everyday sunscreen shouldn’t be your vacation protection. Consider comfort and wearability for the day-to-day. I like lightweight, fast-absorbing lotions with SPF 30 for everyday. Be on the lookout for multitaskers — moisturizers with SPF, or tinted sunscreens that offer coverage and protection.

Days at the beach call for another type of safety. You need:

• Broader spectrum coverage
• Water and sweat resistance
• Higher concentration of active ingredients
• Maybe the spray formulations for reapplications on the fly

A lot of day-to-day sunscreens feel better on your skin, but may degrade more quickly with heavy sweating or swimming. And leave your luxe facial sunscreen at home (you’ll burn through it too fast) if you’re surfing all day.

Complementary Sun Protection Methods

• Sunscreen alone isn't your only defense. Smart sun protection means creating layers of protection:
• Timing: Schedule outdoor activities before 10am or after 4pm when UV rays are less intense
• Clothing: UPF-rated fabrics block more rays than a regular t-shirt
• Accessories: Wide-brimmed hats protect your face, neck and ears better than baseball caps
• Shade: Finding or creating shade cuts UV exposure by up to 75%

PS, don’t forget about protecting your eyes! Sunglasses that block UV rays will help to stop cataracts and protect the skin around your eyes, which is so delicate and so often forgotten as a place that needs sunscreen.

The Truth Behind SPF Numbers

In this post we’ve taken a look at these numbers to determine what they really mean: SPF ratings and the myth that SPF 100 protects your skin better than SPFs of lower numbers.

We now know that the extra UV protection provided by SPF 30 versus SPF 100 is negligible at best, and that other elements, such as application, reapplication timing, and the broad-spectrum protection that’s included, are a lot more important in making sure you’re as effectively sun protected as you can be, rather than just reaching for the highest SPF number.

Your sunblock regimen should consist of applying broad-spectrum sunblocks daily, knowing what your own skin needs and employing correct application techniques.

Don't be fooled by 'Very High' protection marketing claims, look for products that also provide long wave UVA protection, as well as UVB protection. Just remember: The best sunscreen is the one you’ll use frequently and apply properly — no matter its SPF value.