SPF 30 vs SPF 50: Understanding the difference in sun protection

The difference between SPF 30 and SPF 50. From what the SPF rating actually means, to the difference between UVA and UVB rays.

Written by
Stephanie Anderson
Medically reviewed by
min read
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Sunscreen. If you've ever read the beauty secrets of a supermodel, actor or beauty influencer, you've probably heard it a million times.

It's the secret to youthful skin, it works to prevent premature ageing [11][12], and it helps you avoid that awful blotchy skin that comes from catching a few too many sun rays.

Not only that, but it protects you from the increased skin cancer risk that comes with living in Australia [8]. Skin cancer affects 2 in 3 Australians by the time they turn 70, and kills 2,000 Australians a year [1]. Thankfully, it's also very preventable [7], but being proactive is a must.

But if you're new to the daily SPF game and overwhelmed by choice, you're not alone. Ahead, we'll break down absolutely everything you need to know, from what the SPF rating actually means, to the difference between UVA and UVB rays, and more, so that you'll be able to make an educated decision about the best sunscreen for you.

What does SPF mean?

First things first, SPF stands for Sun Protection Factor and is a measure of how effective a sunscreen is at protecting your skin from the sun's ultraviolet (UV) radiation.

The number indicates the level of protection the sunscreen provides against the sun's rays, which are responsible for causing sunburn, premature ageing, and contributing to an increased risk of skin cancer [3].

But what about the number? Well, the SPF number is calculated based on the time it takes for your skin to start getting red or burned when exposed to harmful UVB rays, compared to the time it would take without any sunscreen.

For example, if you were to stand in direct sunlight wearing sunscreen with an SPF value of 15, it would take 15 times longer for your skin to start getting red or burning than if you weren't wearing any sunscreen. If you were to wear SPF 30, it would take 30 times longer than if you weren't wearing any sunscreen.

What's important to note here, though, is that while a higher SPF value does indicate more sun protection, the increase is not linear. For instance, SPF 30 does not provide twice the protection of SPF 15. What's more, no sunscreen can provide 100% protection.

Not only is it essential to reapply your sunscreen regularly, but it's also important to embrace other sun protection measures, like protective clothing and sun-protective hats.

It's also worth mentioning that SPF only refers to protection against the sun's UVB rays. To get comprehensive protection against both UVA and UVB rays, you should always look for a sunscreen labelled broad spectrum. This is because broad-spectrum sunscreens filter and protect against both types of UV radiation [4].

The difference between SPF 30 vs SPF 50

When it comes to sunscreen, SPF 30 and SPF 50 are 2 of the most commonly found. But what's the difference between SPF 30 vs 50?

Well, SPF 30 is estimated to filter 96.7% of UVB radiation, while SPF 50 is estimated to block around 98% of UVB rays. This means that SPF 50 allows slightly less UVB radiation to reach your skin compared to SPF 30 [5].

Where an SPF 30 sunscreen would take about 30 times longer for your skin to start getting red or burning, an SPF 50 sunscreen would take 50 times longer. This is in comparison to if you were not wearing any sunscreen.

What this means is that theoretically, if your skin starts to burn after 10 minutes of sun exposure without sunscreen, SPF 30 would allow you to stay in the sun for about 300 minutes before potential sunburn, and SPF 50 would extend this to about 500 minutes.

If you have fair skin, burn easily, or are planning to spend an extended amount of time soaking up the sun's UVB rays, you might want to opt for a higher SPF. However, don't let the number lull you into a false sense of security.

Regardless of the level of SPF protection claimed, no sunscreen is infallible, so it's still important to take other sun protection measures, as well [10]. It's slip, slop, slap, seek and slide [2] for a reason, after all!

Does SPF 50 last longer than SPF 30?

In short, yes and no. While a higher SPF does offer an extended period of sun protection, the SPF level is not directly related to how long your sunscreen will last on your skin.

You see, while an SPF 50 sunscreen would theoretically allow you more time in the sun than an SPF 30 sunscreen, both options will wear off over time. That's why reapplication is key.

It's also important to note that outside of the SPF factor, there are a number of variables that will affect the duration of protection you get from sunscreen. These include the type of sunscreen, your skin type, sweating, swimming, towel drying, and other environmental factors.

SPF 30 vs 50 aside, sunscreens can and do wear off over time, so it's important to apply sunscreen every 2 hours to maintain effective protection [4][10].

Is SPF 30 enough in Australia?

It's no secret that Australia is known for its strong and intense sun. We have high levels of UV radiation due to our proximity to the ozone hole, which increases the risk of both skin damage and skin cancer. Because of this, using effective sun protection measures is essential.

While SPF 30 can provide decent protection against UVB rays, many health organisations in Australia recommend using sunscreens with a higher sun protection factor, such as an SPF 50 sunscreen.

This provides an extra layer of protection, especially during the peak sun exposure times. Additionally, broad-spectrum sunscreen will protect against both UVA and UVB rays, which offers more comprehensive protection [9].

In Australia, the Therapeutic Goods Administration (TGA) has established rigorous standards for sunscreen labelling and testing. Sunscreens labelled with SPF 50+, like Software’s Daily Sun Defence, have been tested to ensure they meet the required level of protection against UVB radiation [4].

Do you really need to use sunscreen every day?

Yes, using sunscreen every day in Australia is highly recommended, even on cloudy days [10]. Think of sunscreen as an important part of your skincare routine. In Australia, our UV radiation levels are among the highest in the world.

This means we're at risk of developing skin damage, sunburn, premature aging, and skin cancer all year round. Making sunscreen a part of your daily routine is a proactive step to protect your skin and overall health.

Here are some important points to consider:

UV radiation intensity

Even on cloudy days, a significant amount of UV radiation can penetrate the clouds and reach your skin [10]. It can also reflect off surfaces like sand, water, and concrete, increasing your exposure.

Cumulative sun damage

Sun damage is cumulative, meaning that exposure over time adds up. Even short periods of daily sun exposure can contribute to this cumulative damage.

Daily activities

Even routine activities like walking to work, running errands, spending time outdoors or even driving your car [6] can expose your skin to the sun [10]. Using sunscreen as part of your daily routine helps protect your skin during these activities.

Prevention of skin cancer

Using sunscreen consistently can help reduce the risk of developing skin cancers like melanoma, squamous cell carcinoma, and basal cell carcinoma.


Sun exposure accelerates the ageing process of the skin, leading to wrinkles, fine lines, and other signs of premature aging. Using sunscreen daily can help maintain the health and appearance of your skin.

Sunscreen and other measures

While sunscreen is important, it's not the only measure you should take. Wearing protective clothing, seeking shade, using sunglasses and hats, and avoiding outdoor activities during peak sun hours (typically 10am to 4pm) are all important strategies to minimise sun exposure [9][10].

When choosing a sunscreen, it's best to opt for a broad-spectrum sunscreen with a high SPF, such as Software’s Daily Sun Defence SPF 50+. Apply it generously to all exposed skin, and don't forget commonly overlooked areas like the ears, neck, and the back of your hands. Reapply every 2 hours, and more frequently if you're sweating or swimming.

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