Maxiblock Essential SPF 50+ sunscreen tube on an Australian worksite with steel framework and clear sky behind it

What's the difference between SPF 30 and SPF 50 sunscreen for the Australian sun?

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Most people read SPF 50 as a small step up from SPF 30. Under the Australian sun, the real gap is wider than those two numbers make it look.

In Australia, an SPF 50+ sunscreen has to test at 60 or higher, while an SPF 30 is tested to deliver about 30. The "+" is the giveaway: it means the sunscreen scored above the number on the front. Because a 50+ filters at roughly double the rate, about half as much UVB reaches your skin.

Worth noting that the comparison here is against a 50+, not a plain SPF 50. The high-protection sunscreens you'll see on Australian shelves are almost all labelled 50+, so that's the honest like-for-like.

How harsh is the Australian sun?

Very. Australia sits under some of the strongest UV on the planet, and in summer it can take only a few minutes of midday sun before skin starts to burn. The map below shows where UV runs highest across the country. Once the UV index reaches 3, sun protection is worth wearing, right through the year.

Australian January UV index map showing extreme UV areas in red and pink

In much of the country the index sits at 3 or above for most of the day in summer, and well into the cooler months up north. That's the reason daily cover gets recommended here when it might not somewhere milder.

Source: Bureau of Meteorology

Is SPF 30 enough?

Applied properly, an SPF 30 blocks about 97% of UVB, which is plenty for everyday cover. The catch is that hardly anyone applies enough. If you tend to go light, or you're outside for hours in strong summer sun, a 50+ gives you more margin for the under-application that's close to universal.

Whether a 30 or a 50+ suits your face comes down to how much sun it gets day to day. We cover choosing an SPF for your face separately.

Why SPF 50+ gives about double the protection

The key is what reaches your skin, not what gets blocked. An SPF 30 lets through about 1 in 30 UVB rays. A 50+, tested at 60, lets through about 1 in 60. The share blocked barely moves, but the amount landing on your skin is cut roughly in half.

Label Tested SPF UVB Filtered UVB reaching skin
SPF 30 30 ~96.7% ~3.3% (about 1 in 30)
SPF 50+ 60 or higher ~98.3% ~1.7% (about 1 in 60)

This is where the numbers trip people up. Going from blocking about 97% to about 98% sounds like almost nothing. But that's the wrong figure to watch. The number that matters is the slice getting through, and that slice halves.

A food comparison makes it click. A product that's 98% salt-free still contains 2% salt. One that's 99% salt-free contains 1%. That last percentage point doesn't read as much on the label, but it's half the salt. UV works the same way. It's the light reaching your skin that counts, so moving from SPF 30 to a 50+ roughly halves what gets through.

The same logic shows up in burn time, with one big caveat: these are lab figures. In a test, if bare skin burns in 5 minutes, an SPF 30 stretches that to about 150 minutes and a 50+ tested at 60 to about 300. Those numbers assume you've applied the full test dose, which almost nobody does, so read them as a ceiling rather than a promise.

Under the Australian sunscreen standard, AS/NZS 2604:2012, a typical SPF 50+ gives about twice the UVB protection of a typical SPF 30. That figure is specifically about UVB, the rays that burn, which is what SPF measures.

Does a higher SPF have any downsides?

A few:

  • Higher-SPF formulas usually carry more UV filters, so they can feel thicker on the skin and take more work to rub in.
  • Some sensitive skin reacts to the extra filters too.
  • The bigger risk, though, is human: a high number can lull you into thinking you're covered, so you skip reapplying.
  • If a 50+ feels heavy for everyday wear, a lighter everyday SPF 50+ can be easier to live with day to day.

What about UVA?

SPF only measures UVB, the rays that burn. UVA goes deeper into the skin and is a major driver of ageing and longer-term skin damage. That's why the SPF number is only half the picture. On the label, look for the words "broad spectrum," which means the sunscreen is tested to filter UVA as well.

It's also why the 2012 Australian standard added UVA testing that older sunscreens never had to meet. Both mineral and chemical filters can be broad spectrum, and we compare the two in mineral vs chemical sunscreen.

How to get the protection on the label

The SPF rating assumes a thick, even layer that most of us never quite apply. The simplest fix is two passes: put it on, let it dry, then go over the same spots again. That gets you closer to the amount the rating was tested at, without measuring anything.

After that, top it up every couple of hours, and again after swimming or towelling off. We break down how often to reapply sunscreen in more detail.

Get the application right, and the gap between SPF 30 and SPF 50 matters far less than the gap between sunscreen that's on your skin and sunscreen that's still in the bag.