Do you know what the SPF numbers mean?

There are a lot of numbers when it comes to sunscreen and as a health professional I think it’s important to understand what they actually mean to better lower your risk of sun damage.  Here are a few of the key messages I think are important to help keep you a little more protected;

  • Sunscreen alone is not a bulletproof shield against skin cancer.
  • You need to apply sunscreen properly to reach the specified SPF level (did you know scientists use about double the amount applied by the average person to determine a product SPF rating).
  • A kaftan cover up or white cotton shirt is not reliable clothing for great sun protection, sometimes only giving you SPF 5.
  • It takes 11 minutes in the sun with no protection for irreversible damage to begin to occur.
  • Prevention is better than treatment, so don’t burry your head in the sand when it comes to wearing sunscreen.

On your skin - What do the SPF numbers mean?

Sun Protection Factor (SPF) is a guide applied to a sunscreen and cosmetic product about their ability to prevent UV from damaging the skin.

Sunscreens: Are products that help prevent the sun's ultraviolet (UV) radiation from reaching your skin. There are two types of ultraviolet radiation, UVA and UVB, which damage the skin, age it prematurely, and increase your risk of skin cancer. UVB is the chief culprit behind sunburn, while UVA responsible for wrinkling and ageing.

However, sunscreens vary in their ability to protect against UVA and UVB and a broad-spectrum sunscreen is recommended as it filters both.

SPF numbers? The SPF number indicates how long you can stay in the sun before your skin reddens.  

How long? This depends on the time of day, time of year, how cloudy it is, amount of UV reflection and skin type. So if it takes 10 minutes for your unprotected skin to start turning red, using an SPF 15 sunscreen theoretically prevents reddening 15 times longer — about 150 minutes, SPF 30 will provide 30 times more protection than those first 10 minutes - 300 minutes, SPF 50+, 500 minutes.  Whilst the numbers sound big the improvement from SPF 30+ (96.7%) sunscreen filter to SPF50+(98%) is only small and it really doesn’t take long for the sun to damage your skin.

How much and how often? More important than your SPF strength is how much sunscreen you apply and how often.   Most people apply way too little and forget to re-apply every 2 hours regardless of the SPF. It is recommend for the average person about 35 mls of sunscreen (7-10 teaspoons) for the whole body.  Keep in mind your daily activities and smudge sunscreen remove it such as when wearing clothing, swimming or lying on your towel.

On your body (UPF)

Ultraviolet protection factor (UPF) is a rating applied to the effectiveness a piece of clothing shields against the sun. The UPF level listed on garments such as rash tops are based on the content, weight, colour, and construction of the fabric, and indicates how much UV can penetrate the fabric.

Clothing with a UPF50 rating allows just 1/50th of the sun’s UV radiation to reach your skin, this would provide excellent sun protection. A kaftan or thin white t-shirt dress has a UPF5 allowing 1/5th of UV through therefore provides a low level of protection. Wet clothes let though even more UV.

My top 5 sun safe tips:

20 minutes: before you go outside apply your sunscreen to give it enough time to attach to your skin.

7 teaspoons: is the minimum amount of sunscreen you should be covering your body with. Use 1 teaspoon per limb, front, back of body & face = 7 teaspoons (or 35mls in total).

2 hours: reapply sunscreen every two hours - no sunscreen, regardless of strength, should be expected to stay effective longer than two hours without reapplication. Plus your daily activities can remove it such as when wearing clothing and even just lying on your towel.

Date: your sunscreen has an expiry date – check it! You want to be sure that the active ingredients you are relying on for protection don’t become inactive when expired. The same goes for leaving it the sun or car – keep your sunscreen somewhere cool and shaded.

Cover up: with extra layers of protection such as a hat, sun protection clothing with a UPF rating and sunglasses.

Remember sunscreen alone is not a suit of armour against preventing sun damage. That’s why our Aquacove® mission is to make being sun smart easier by making beautiful, UPF 50+ products to help you love your skin a little more.


“Correct sunscreen applications reduces skin cancer”, The Sydney Morning Herald. January 17, 2015.

Sunscreen, SunSmart Fact Sheet, Cancer Council Victoria

Styling you, Nivea SunSafe Code;

Skin cancer foundation: