Howdy, summer: Here’s how much sunscreen you actually need to put on.

Do you ever feel like you’re fighting an uphill battle when it comes to avoiding a sunburn even when you slather on sunscreen?

Do you ever find yourself staring at the wall of sunscreens at your local chemist or grocery store and feeling completely overwhelmed at all the confusing labelling?

Me too.

Technically, 85 percent too. That’s how many of us don’t actually know how much sunscreen to use to avoid getting sunburnt according to Clinical Associate Professor Saxon Smith.

Dr Smith is an Australian trained dermatologist and holds a fellowship with the Australasian College of Dermatologists. He gave up some of his time to let me ask every question under the sun (see what I did there?) about sunscreen, sunburn and what on earth all the science jargon on labels actually means.

How much sunscreen and how often?

Almost all of us are coming back from a day in the sun cursing the sunscreen we are using for not protecting our skin from sunburn, when in fact we’re often not putting enough on, or often enough.

Dr Smith says, “we need to apply one teaspoon of sunscreen per limb and half a teaspoon for your face”. To cover the whole body, it’s “seven teaspoons, or 35 to 40 mls of sunscreen, basically the size of a golf ball”.

Dr Smith explains that sunscreen should be reapplied at least every two hours, adding that “30 to 40 percent [of us] never reapply their sunscreen”.

“As the sunscreen does its job, it deteriorates,” he continues. “The molecule is more rapidly destroyed when you add swimming, sweating and having beach sand rubbing against your skin.”

Let me award you with a Bachelor of Science majoring in sunscreen.

Hands up if you feel like you actually need a degree to understand the sunscreen labelling? In Australia, sunscreens are regulated by the TGA which also regulates medicines, and sunscreens, like those made by Banana Boat, have to adhere to very strict rules. Here’s your science degree in under a minute courtesy of Dr Smith:

There are three types of sun rays. UVC is the most damaging, but our stratosphere filters that one out for us. UVA rays cause sun ageing and contribute to skin cancer. UVB rays are the sunburn ones and are linked with causing skin cancer and linked to sun damage and skin ageing.

SPF, or sun protection factor, is how much UVB protection you are getting. The higher the number after SPF, the more protection. SPF30 sunscreen filters 96.7 percent of UVB radiation and SPF 50 filters 98 percent.

UVA isn’t as simple to score, but in Australia we have “broad spectrum” which refers to the UVA protection.

“The trick is the higher SPF and broad spectrum, the higher protection against UVA and UVB rays you are getting,” says Dr Smith.

As for the numbers, they mean that you are protected from sunburn, wearing sunscreen, a certain amount more than you would without sunscreen.

For example, Dr Smith says, “if you naturally burn within five minutes of being out in the midday sun, that means with an SPF50, you get 50 times five minutes worth of protection. Notwithstanding the impact of swimming and sweating.”

The new Banana Boat Dry Balance SPF50+ Sunscreen ticks all the boxes with its high SPF and broad spectrum. As a bonus, it dries with a soft matte finish so there is no sticky greasy feeling. It's also four hours water resistant - perfect for those beach days!

But if it's four hours resistant, why reapply every two hours?

Australia is different to other countries in its water-resistant testing and standards for sunscreens. In Australia, the SPF has to be the same at the end of its claimed water-resistant promise, where as in other countries, the SPF can drop to 25 percent at the end of the promised time.

Dr Smith says, “If you are spending four hours in the water, you are still getting the same protection at the end of the four hours as you started with,” BUT… “You need to reapply every time you jump out of the water.”

It’s not only about sunscreen…

The latest SunSmart campaign includes five steps to protection against sunburn. For those that need a refresher:

Here are five tips to help you stay safe in the sun this summer:

1. Apply sunscreen liberally and always use at least seven teaspoons per application
2. Always apply sunscreen at least 20 minutes before sun exposure and allow it to dry on the skin
3. Always reapply sunscreen every two hours, and more often if swimming, sweating or after using a towel
4. Always wear protective clothing, wide-brimmed hats and sunglasses
5. Seek shade between 10am-3pm and try and avoid prolonged sun exposure

Another tip to remember, don’t forget those easy-to-forget areas (which are the most common to burn) such as the back of the neck, ears and chest.

But maybe I’m allergic to sunscreen…

If you don’t want to go to a dermatologist for patch testing, Dr Smith suggests “at home, apply the sunscreen twice a day on a small area on your forearm. Do this every day for two weeks to see if you develop an allergic reaction.”

Sunscreen works forever right?

Nope. Sunscreens actually have expiry dates (brand new information to me). Dr Smith says, “65 percent of Australians don’t check the expiry date of their sunscreen”.

On top of that, most sunscreen says store below 30 degrees Celsius for a reason. “The sunscreen protection crashes by 40 percent when left in a hot car for two weeks,” says Dr Smith.

Curing a sunburn.

While I had an expert on hand, I decided to ask what to do in the event of getting a sunburn (Dr Google has never been that helpful).

“A sunburn is a burn - a cool shower followed by cool moisturiser (you can pop it in the fridge for a couple hours) will help,” Dr Smith adds. “Get the heat out as soon as you can, but avoid using ice as it will cause more damage. Then, stay out of the sun to avoid getting another sunburn.”

Any more questions? Or your personal tips for staying sun safe? Share with us below.

This content was created with thanks to our brand partner Banana Boat.