What is SPF? Plus everything you need to know about sunscreen

SPF, or sun protection factor, is the scientific measure of the level of protection a sunscreen provides from UVB rays (the UV rays that burn the skin) and the amount of time the sunscreen protects the skin from burning.

The higher the SPF number, the greater the protection factor. In Australia, which has some of the world's strictest sunscreen standards, SPF ratings usually start at 15 and are capped at 50 (it's why you'll never see some of the odd SPF numbers, like SPF83, that you might find on sunscreens sold overseas).

It's important to remember that SPF is not a standardised measure of protection from UVA rays. But the higher the SPF rating, the more protection you will receive from UVA rays.

A broad-spectrum sunscreen will filter both UVA and UVB rays. That kind of protection is what you want because these two UV wavelengths impact the skin in different ways: UVA rays penetrate deep into the skin where they gradually destroy elasticity and can cause dark spots and pigmentation, while UVB rays are primarily responsible for sunburn. Both UVA and UVB rays contribute to increased skin cancer risk.

That number after ‘SPF’ is a measure of how well the sunscreen blocks UVB rays and protects sunscreen-coated skin.

SPF15 protects from 93 percent of UVB rays and 15 times your burn time (the amount of time it takes for your bare skin to burn); SPF30 protects from 97 percent of UVB rays and 30 times your burn time; SPF50 protects from 98 percent of UVB rays and 50 times your burn time.

It's really important to remember that any sunscreen sold in Australia must adhere to our strict standards (which tend to be much higher than those overseas – thanks, ozone!), so it’s good to bear that in mind when choosing your sunscreen.

It doesn’t work that way, and ‘SPF maths’ don’t add up. Layering multiple SPF products doesn’t increase the level of protection – you’ll only receive the amount of SPF protection provided by the highest rated product that you apply.

We can’t say this loud enough: yes! Applying sunscreen every single day, rain, hail or shine, should be a habit, just like brushing your teeth. The sun rises every morning, even if you can't see it, and those UV rays are damaging your skin, even if you can't feel them. So don't think that just because you don't see sunburn, nothing is happening. Sunburn is an immediate reaction, but sun damage accumulates over a lifetime.

Also consider this fact: if you're spending time and money on your skin, and you're not wearing sunscreen every day, you may be undoing all your hard work in trying to keep your skin looking radiant. The sun is responsible for a range of skin issues, from pigmentation and loss of firmness, to premature ageing signs like wrinkles. And we know prevention is better than cure, which is why skin experts recommend sunscreen as the number one step you can incorporate into your skincare routine.

Have we convinced you?

That all depends on your skin type!

Oily or combination skin type should look for lightweight sunscreens, like gels or lotions, that are labelled non-comedogenic. Alternatively, mattifying formulas would also suit combination skin types. We love MECCA COSMETICA's To Save Face SPF50+ Superscreen, MECCA MAX's SCREEN SAVER SPF30 Broad Spectrum Facial Sunscreen and Naked Sundays SPF50 Clear Glow Radiant Sun Serum, which may reduce the risk of some skin cancers while balancing out skin and keeping shine at bay.

If you have dry skin, look for SPF creams that double as moisturisers, or formulas with hydrating ingredients, like hyaluronic acid, glycerin or ceramides. Try MECCA COSMETICA'S To Save Face SPF 50+ Brightening Sun Serum, Dermalogica's Dynamic Skin Recovery SPF50 or Go-To's Nifty Fifty, all of which can also aid in the prevention of premature skin ageing.

And if you have normal skin, you're basically an ideal match for any type of sunscreen and might like to pick and choose your SPF depending on how your skin is feeling on any given day. A couple on our list: MECCA COSMETICA'S To Save Face SPF30 Facial Sunscreen and Naked Sundays Collagen Glow 100% Mineral Sunscreen. These formulas may reduce the risk of some skin cancers - which is the most important thing!

Learn more about choosing the right sunscreen for your skin type.

*ALWAYS READ THE LABEL AND FOLLOW THE DIRECTIONS FOR USE. Sunscreen is only one form of sun protection. Avoid prolonged sun exposure and reapply as directed.

It all comes down to the active ingredients used to provide UV protection, and how these ingredients work on the skin.

Chemical sunscreens, with ingredients like octinoxate and avobenzone, absorb or filter UV radiation and convert it into heat energy, which is then released from the body. These sunscreens are usually lighter and generally rub into the skin more easily.

Physical or mineral sunscreens, with ingredients like zinc oxide and titanium dioxide, act as a physical barrier, absorbing and deflecting UV radiation. It's for this reason that physical or mineral sunscreens are often thicker, and may require a little more effort to work into the skin.

Recently, some skin experts have started referring to these types of sunscreens by different names: chemical sunscreens are known as 'organic' sunscreens, and physical sunscreens are 'inorganic' sunscreens. Read more on the difference between chemical and physical sunscreen.

Sadly not. Any skincare or cosmetic product with SPF, like a moisturiser or foundation, is considered a secondary sunscreen because they are formulated for a primary purpose other than sun protection, like hydrating your skin (moisturiser) or evening out your tone (foundation).

Dedicated sunscreen products are considered a primary sunscreen because their one job in life is to shield your skin from sun damage, and in Australia and New Zealand these products are strictly tested, rated and regulated by the TGA (Therapeutic Goods Administration).

The smart thing to do: use a dedicated sunscreen every day. It’s not your moisturiser or foundation’s responsibility to protect your skin against sun damage, so don’t put that on them – it’s a big job! Feel free to layer them on top though.

To ensure you get the maximum level of protection offered by your sunscreen, there are two important things to do.

Use the right amount. Sunscreen is not the product you want to be skimping on. The current Cancer Council recommendation is 5ml (or one teaspoon) of sunscreen to the face, neck and ears, and an additional 5ml to each limb, the front of your torso, and the back of your torso. This adds up to around 35ml (or seven teaspoons) for a full body application of sunscreen. Yes, that much.

Apply sunscreen in the morning, on clean and dry skin, and give it 20 minutes. All sunscreens, physical and chemical, need this time to create a protective barrier before you step outside and expose yourself to UV rays. And be diligent about reapplying sunscreen every two hours. This is crucial to ensure your skin is protected all day long. Learn how to reapply sunscreen without ruining your makeup (it is possible!).

*ALWAYS READ THE LABEL AND FOLLOW THE DIRECTIONS FOR USE. Sunscreen is only one form of sun protection. Avoid prolonged sun exposure and reapply as directed.

If you're using a sunscreen that’s not right for your skin type (say, if it’s too thick or oily for your skin, or made with clogging comedogenic ingredients), then yes, it is possible that a sunscreen might make you break out.

But that doesn’t mean you get a pass. It just means you need to do a little research to find your sunscreen. Think of how much time you spend finding your ideal foundation or perfect red lipstick – this is just as important and the health of your skin depends on it.

Yes, you really do. The skin on the lips is incredibly delicate, but even the most diligent SPF enthusiasts among us often forget to shield them with sunscreen. The easiest way to ensure you’re protecting your pout is to use a lip balm with SPF.

*ALWAYS READ THE LABEL AND FOLLOW THE DIRECTIONS FOR USE. Sunscreen is only one form of sun protection. Avoid prolonged sun exposure and reapply as directed.