Chances are you've been putting on sunscreen wrong. Here's how to do it properly.

We wouldn’t go to the beach (or out in summer in general) without a bottle of sunscreen, but just taking it along – or even just applying it once – isn’t enough to protect your skin.

“Most Australians also don’t apply enough sunscreen or reapply often enough,” says Craig Sinclair, Chair of Cancer Council Australia’s Skin Cancer Committee.

“Make sure you apply your sunscreen twenty minutes before heading outdoors and reapply every two hours. You should reapply more regularly if you are swimming, sweating or towel drying.”

In terms of the amount you should be applying, Cancer Council Australia recommends at least a teaspoon for each limb.

"The average adult should use at least a teaspoon for each limb, one teaspoon for the front of the torso, one for the back, and one for the head," Sinclair says.

"This means a full adult application would be around 35ml and a 100ml litre bottle is only really enough for three full body applications."

Listen: The sunscreen pact we all need to make. Post continues after audio.

In the wake of a number of recent complaints of sunscreen failing to protect skin against sunburn, he has some important tips.

"If you are using sunscreen it’s important that it’s used in combination with other sun protection measures and applied correctly. If it’s a new bottle, follow the label directions and patch test first," he says.

"Remember, sunscreen is designed to help slow down the burning process, but no sunscreen provides 100 per cent protection and it shouldn’t be relied on as a suit of armour against UV. It should be used as the last line of defence."

You can download the SunSmart app at cancer.org.au/sunsmartapp to access all the information on UV levels and recommended sun protection.