What Does SPF Actually Mean?

What do the numbers and letters correspond to when it comes to sunscreen? UVA, UVB, PA+++, broad spectrum… and then there’s SPF 15, 30, 50, even 100. What does SPF mean? And more importantly, which one should you be wearing every day?

At PoolBar London, we’re here to keep things simple. Think of this as your one-stop guide to SPF, no confusion, just the facts.

SPF stands for Sun Protection Factor. It measures how well a sunscreen shields your skin from UVB rays, the main cause of sunburn. The number tells you an estimated amount of time you can stay in the sun without burning compared to bare skin without any SPF.

So, SPF 30 theoretically means it would take 30 times longer to burn, assuming you’ve applied enough and have reapplied when necessary.

For instance, if your skin usually starts to burn after 15 minutes in the sun, applying SPF 30 could keep you protected for about 7.5 hours. Of course, in real life, factors like swimming and sweating can shorten that time, so think of it as maximum potential, but not a free pass to sunbathe all day without reapplying.

Here’s the catch: SPF only covers UVB, not UVA. UVA rays penetrate deeper, quietly contributing to premature ageing, pigmentation, and long-term DNA damage. You can learn more about the difference between UVA & UVB rays in our blog post.

That’s where broad-spectrum sunscreen comes in. These products protect against both UVA and UVB rays, giving you all-round coverage: immediate sunburn protection plus long-term skin health. In short, broad-spectrum is your ticket to glowing, protected skin without compromise.

So, SPF tells you about sunburn protection, but it’s only one piece of the puzzle.

Now for the numbers on your bottle. SPF doesn’t work on a straight scale where SPF 50 is double SPF 25. Instead, it’s about the percentage of UVB rays filtered out:

• SPF 15 blocks around 93% of UVB rays
• SPF 30 can block about 97%
• SPF 50 blocks roughly 98%
• SPF 100 can block around 99%

SPF 50 isn’t double SPF 30, it just gives you that extra edge, which can matter if you’re fair-skinned or outdoors for longer periods.
So should you always reach for SPF 50? Not necessarily.

Dermatologists recommend SPF 30 or higher for everyday wear. Both give you strong, reliable protection, the best sunscreen is the one you’ll actually use consistently. SPF 100 isn’t necessary for daily use.

PoolBar makes it simple: our body SPF in SPF 30 and 50, while our face SPF is SPF 50, so you can choose what works best for your routine without overthinking it.

A golden rule is that no sunscreen blocks 100% of UV rays. Even SPF 100 lets about 1% through, and over hours of exposure, that adds up. That’s why relying solely on the SPF number isn’t enough, how you apply it matters just as much.

To get all day protection, follow these steps:

• Apply generously, about 2 tablespoons for your body and a teaspoon for your face. Most of us don’t use enough, and under-application can halve your SPF.
• Reapply every 2 hours, and straight after being in water or sweating.
• Don’t forget the tricky spots like ears, scalp, lips, backs of hands, and tops of feet. These often get missed but still need coverage.

Sunscreen isn’t a “slap it on and forget” product, it’s a routine. Make it part of your daily ritual, like your morning coffee or brushing your teeth, and your skin will thank you for years to come. For more information on how to apply sunscreen for maximum protection, check out this post.

We’ve already mentioned UVA rays, but let’s clarify further. This is PoolBar’s way of remembering the difference between the two.

• UVB = Burning
• UVA = Aging

UVA rays also penetrate through the clouds and through windows, meaning you’re exposed even indoors or on grey days. That’s why dermatologists insist on broad spectrum SPF.

In the US, make sure your sunscreen says “broad-spectrum” on the label to confirm it shields against both types of rays. If you’re in the UK, look for the UVA star rating. For the EU, check for the UVA in a circle symbol. These show that the sunscreen protects against UVA as well as UVB.

At PoolBar, our mineral SPFs are broad spectrum by design, giving you the complete shield.

Your face is on show 24/7, which makes it more vulnerable to UV exposure. The skin here is thinner and more delicate than the rest of your body, which means it loses moisture faster, shows signs of ageing sooner, and is more prone to pigmentation from sun damage.

That’s why face sunscreens are usually lighter and formulated with extra skincare benefits like antioxidants and hydration. PoolBar’s Face SPF 50 was made exactly for this: light, non-greasy, and designed to wear under makeup.

Body SPFs are designed for easy application across larger areas, often with a slightly richer texture to help you cover arms, legs, and torso efficiently.

With PoolBar Body SPF, you get protection that’s easy to apply, water-resistant, and scented with coconut and vanilla.

Fairer skin has less melanin, which means it burns more easily and is more prone to long-term damage like pigmentation and premature ageing. For daily protection, SPF 50+ is ideal, especially if you spend extended periods of time outdoors.

Darker skin tones have more melanin, which provides some natural protection against UVB, but it doesn’t prevent all damage. SPF 30 or higher is still essential to protect against sunburn, pigmentation, and long-term skin harm.

Oily and/or combination skin, should avoid thicker creams that can feel heavy and clog the pores, making daily use feel like a chore. Use mattifying formulas, so your skin feels fresh and protected without adding extra shine.

Sensitive skin is prone to irritation, redness, or reactions, so it needs extra gentle protection. Focus on dermatologically tested and sunscreen free from harsh ingredients like octinoxate, oxybenzone, and parabens – like PoolBar’s.

Dry skin has more risks with sun exposure as it can dry out skin further, so SPF that hydrates while protecting is a must. Find ingredients like hyaluronic acid and ceramides to lock in moisture, leaving skin soft, smooth, and protected from UV damage at the same time.

Sun care isn’t just about avoiding burns, it’s about protecting your skin, keeping it healthy, and feeling confident every day. With PoolBar’s mineral sunscreen range, you can make daily sun protection feel easier.

Make sun protection part of your everyday glam. Shop PoolBar SPF now and step out with confidence, wherever your day takes you.