What Does SPF Mean?

You’d think choosing a sunscreen would be a relatively simple task in this day and age, wouldn’t you? But nowadays we’re bombarded with options – sport, sensitive, kids, moisturising, anti-aging, spray… You name it, they’ve got it. It never ends! One factor most people consider but don’t know a lot about is the SPF. So, this blog will shed some light on the most important things you need to know about SPF.

The basics

Choosing the correct SPF rating seems easy but is it really? Let’s start with the basics: what does SPF stand for? SPF stands for sun protection factor. That’s greats, but what does SPF mean? SPF measures a sunscreen’s ability to protect you from dangerous UVB rays, which cause sunburn and increase cancer risk.

And how does that work with different factors? Is it really as simple as SPF 30 offers twice as much protection as SPF 15? If you answered yes, think again.

Well, the SPF refers to how much UVB light will reach your skin when you apply your sunscreen properly. To clarify, properly means in high enough quantities, to all exposed parts of your body and reapplying regularly. But how much coverage are you actually getting?

If your sunscreen of choice is SPF 15, you’re reducing UVB radiation to about 1/15th of its original strength. That means you’re getting around 93% coverage. Or if you prefer SPF 30, you’re reducing UVB radiation to 1/30th and getting around 97% coverage. In other words, the exposure time needed to burn is increased by a factor of 15, 30 or whatever the SPF you decide to use is. In short SPF 30 is nowhere near twice as effective as SPF 15.

What SPF is best for me?

What about even higher factor sunscreens? Is it worth buying SPF 50 and up? Well, in some countries sunscreen companies weren’t allowed to market sunscreens higher than factor 30+ until recent years. That’s because there’s not a huge difference when you get past factor 30. It’s gimmicky and it gives consumers a false sense of security. Just because you’re wearing factor 100 doesn’t mean you’re 100% safe!

For the record, with factor 50 you get around 98% coverage and with factor 100 you get around 99%, so it’s not a big step up from factor 30. When you look at it like that it’s easy to understand why some regulatory bodies have capped SPF of sunscreens at 50+. But should you bother buying the higher stuff?

The Skin Cancer Foundation recommends using SPF 15 for day to day wear, or SPF 30 or higher for extended outdoor activity as well as additional sun protection methods such as staying in the shade or wearing protective clothing.

How much and how often should I reapply?

Another important question you might be asking yourself is, “How long can I go before I need to reapply?” Good question! Generally speaking, it takes about 10 to 20 minutes without sunscreen for your skin to start burning. That means an SPF 15 product should protect you 15 times more. But does that mean it protects you for 15 times as long?

A lot of people think so but that’s oversimplifying. The US Food and Drug Administration stress the importance of factoring in time of day and UV index. Think about it – do you get burnt equally as fast first thing in the morning as you do at noon? Not me. And, unsurprisingly, solar intensity is greater on clear days than cloudy days. Seems logical enough.

So, back to the point, just because your factor 15 offers you 15 times more protection doesn’t mean you’re literally safe for 15 times as long. Regardless, you should be reapplying every 2 hours and directly after swimming, towelling off, playing sports or if you sweat a lot.

But there’s more to it than that. Fair-skinned people are also likely to absorb more solar energy than their darker counterparts. And how much sunscreen you apply also plays a role in how much solar energy you absorb. So you better make sure you’re using enough. The Australian Cancer Council says you should use about a teaspoon (5ml) of sunscreen per limb, one for your back, and one for your front. That’s seven teaspoons (35ml) all up for the average adult. They also say most people use about half as much sunscreen as is really needed. Pretty scary if you ask me!

One final thing you should know is that the SPF doesn’t take into account UVA rays. UVA rays don’t burn the skin but they contribute to premature aging and skin cancer risk, so it’s important to make sure your sunscreen also offers UVA protection. To get the best of both worlds, look for a broad-spectrum sunscreen.

What should I take away from all of this?

• SPF measures a sunscreen’s ability to protect your skin from damaging UVB rays.
• For day-to-day activities SPF 15 offers good protection, for the beach and the pool or extended periods outdoors, SPF 30 or higher is the way to go.
• Make sure your sunscreen is broad spectrum! SPF doesn’t protect you from UVA rays.
• Wearing SPF 15 does not mean you can literally stay in the sun for 15 times as long as it would take you to normally burn.
• Factor in UV index and time of day when spending time in the sun.
• Be sure to put on enough sunscreen in the first place – that’s seven teaspoons (35ml) per average adult and reapply regularly.
• Don’t just rely on sunscreen! Wear protective clothing and if you can stay in the shade.

I really hope this article has cleared up a few things about the meaning of SPF for you. It definitely dispelled a few myths for me! Without a doubt I’ll be passing on my newfound knowledge to family and friends.

What SPF do you usually use? Will you keep using the same SPF going forward? I love hearing from readers, so leave me a comment below and let me know what you think.