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SPF 101 – What does SPF stand for and why does it matter?

22 December 2021|2 min read

So, you’re interested in finding out more about sun protection – such as how does sunscreen work

Looking after your skin is not only one of the best ways to look good, but it’s also a huge part of keeping healthy. We’ve all heard about the downfalls of sun damage. And if avoiding the characteristics of aging skin aren’t enough motivation, hopefully staying fighting fit is. 

So, let’s talk about all things SPF with Dermatologist, Dr Liz Dawes-Higgs.

What is SPF? 

SPF stands for Sun Protection Factor. 

It’s basically a rating that certain products have in order to help consumers understand how much protection the product may give the user from the sun.

The number refers to how much more sun protection the application gives you. 

Dr Liz explains, “For a person who experiences skin redness after ten minutes in the sun, an SPF 30 sunscreen should protect their skin for around 300 minutes.”

We’ll explain more about each SPF rating below. 


SPF stands for Sun Protection Factor.

What is the highest SPF you can buy? 

The highest SPF sunscreen you can buy in Australia is 50+ which blocks 98% of Ultraviolet Radiation (UVR) when applied correctly. Pretty impressive, right? 

Is there an SPF 100? 

Unfortunately, not in sunscreens. But you may have seen other sun protection stuff – like sunnies or rash vests labelled with UV400 protection. This just means they have been developed to block 100% of UVR. 


SPF 50 covers you 98% from UVR.

What are the differences between SPF 15, SPF 30 and SPF 50?

Are you ready for some more numbers? 

Sunscreen starts at an SPF rating of 4. Although this number seems tiny, products labelled with an SPF of 4 may protect your skin against 75% of UVR. Products labelled SPF 8 protect against 87.5% of UVR. While this might seem quite high, these lower SPFs generally aren’t recommended by dermatologists. 

SPF 15 protects against 93.3% of UVR. If you want to know if SPF 15 is enough for a day-to-day cover, the Cancer Council says no. They recommend slopping on a sunscreen that's SPF 30+ or higher.  

Dr Liz says, in the case of SPF 15, “It’s better than nothing. But I recommend SPF 30 or higher in Australia.”

Now we’re getting into the good stuff. 

SPF 30 protects your skin from a whopping 96.7% of UVR, so this is the lowest rating you may want to pop in your shopping cart. The difference between SPF 15 and SPF 30 may only seem a small percentage, but it translates into nearly twice the protection in terms of UV exposure. 

SPF 50 covers you 98% from UVR, which is the highest rating and therefore the winner of the pack. 

Should I use a moisturiser with SPF?

According to Dr Liz, it’s not only important, but it’s also efficient no matter your skin type.

“Using a moisturiser with an SPF reduces a step! Or, as most sunscreens come in a moisturising base, you don’t always need a moisturiser first – just go straight to the sunscreen. Especially if you have oily skin,” she says. 


Dr Liz says SPF 15 is “better than nothing. But I recommend SPF 30 or higher.”

Sunscreen is a daily routine 

Dr Liz wouldn’t be a dermatologist if she didn’t take the opportunity to remind us that we should be using sunscreen daily. Anytime the UV index is above 3, which is for around ten months of the year in Australia, you need to apply SPF 30 or higher. 

“And remember to be generous with your application. We often don’t apply nearly as much as what is used during product testing which may decrease effectiveness,” Dr Liz says. 

Sunscreen is only part of the solution. 

For a person who experiences skin redness after ten minutes in the sun, an SPF 30 sunscreen should protect their skin for around 300 minutes.

- Dr Elizabeth Dawes-Higgs

Children of the 90s may remember the Slip, Slop, Slap campaign – slip on a shirt (or other covering), slop on some sunscreen, slap on a hat. Now the SunSmart campaign, jointly funded by Cancer Council Victoria and the Victorian Government, includes ‘seek’ some shade and ‘slide’ on some sunnies. 

Dr Elizabeth Dawes-Higgs is an award winning dermatologist with extensive experience in the world of medicine, business leadership and education. She is passionate about a range of topics including laser dermatology, the treatment of scarring and skin cancer management.

Reviewed by the healthylife Advisory Board December 2021.


This article is for informational purposes only and does not provide medical advice, diagnosis, or treatment. Any information published on this website or by this brand is not intended as a substitute for medical advice. If you have any concerns or questions about your health you should consult with a health professional.