What is the Best Sunscreen

As a skin cancer doctor, this is one of the most common questions I’m asked in the clinic - almost daily.  And, my answer is always the same: The best sunscreen is the one you will actually wear.

A big part of my job is helping patients prevent sun damage in the first place - not just treating it when it appears.  You can buy the most advanced formula in the world, but if it feels too greasy or uncomfortable on your skin, it’s going to stay on the shelf. Compliance is the most important factor in sun protection.

SPF 30 vs. SPF 50: Does it matter?

Ideally, you should reach for an SPF 50+, but don't be discouraged if you prefer the feel of an SPF 30+.

• SPF 30 filters approximately 96.7% of UVB rays.

• SPF 50 filters approximately 98%.

  
  

While that 1.3% difference seems small, SPF 50+ provides a vital safety margin. Most people under-apply their sunscreen. If you under-apply SPF 50, you might still be getting SPF 20-25 protection. However, if you under-apply SPF 30, your actual protection could drop to SPF 10-15—filtering as little as 90% of UV rays.

If an SPF 30+ formulation is the only one you enjoy wearing, using it correctly is better than not using any at all.

The "Shot Glass" Rule

To achieve the protection listed on the bottle, you need to apply a significant amount. In practice, I often see patients under-applying sunscreen, which significantly reduces its effectiveness.  A good rule of thumb is one teaspoon per body region:

• Head and neck

• Chest and abdomen

• The back

• Each arm and leg

  
  

This equates to roughly 30ml (a full shot glass) for a full-body application. Be wary of spray-on sunscreens; they often fail to provide enough coverage, especially if it’s windy or if you aren't spraying heavily enough.

Timing and the "Double Coat"

For those with fair skin or a history of sun damage, I recommend the double-coat method: apply your first layer, wait a few minutes, and apply a second. This ensures you haven't missed any spots. Remember: Apply, wait 20 minutes, then go out.  Sunscreen in general, isn't an instant shield. It needs 20 minutes to bind to the skin and "set" before you head outdoors. This is particularly crucial for chemical filters.

Reapplication is non-negotiable

Sunscreen wears off and breaks down. You must reapply at least every two hours. If you are swimming, sweating, or towel-drying, you need to reapply immediately afterward, regardless of how long it has been.

Two "Must-Haves" for your label

Beyond the SPF number, there are two more features your sunscreen is recommended to have to be most effective:

1. Broad-Spectrum Protection SPF only measures protection against UVB rays (the ones that cause sunburn). However, UVA rays penetrate deeper into the skin, causing premature aging, wrinkles, and long-term DNA damage. Always look for the words "Broad Spectrum" on the bottle. This ensures the formula has been tested to shield you from both UVA and UVB.

2. Water Resistance Even if you aren't planning on taking a dip, moisture is the enemy of your sun shield. Humidity and natural perspiration can cause sunscreen to "drift" or break down. Choosing a formula labelled "4 hours water resistant" ensures the product adheres more effectively to the skin during physical activity. Just remember water-resistant does not mean "waterproof."

The Australian Standard

Australia’s sunscreen standards are a global gold standard. Beyond the initial TGA approval required for all SPF 30+ and 50+ labels, we are seeing a new era of TGA transparency and enforcement in 2026. The regulator is currently refining how sunscreens are classified to ensure patients can easily choose the right level of protection. This active 'checks and balances' system ensures that despite occasional media reports, the products available to you remain a safe and reliable tool in skin cancer prevention.

About the Author

Dr Danika Fietz is a Skin Cancer Doctor with over a decade of experience in diagnosing and treating skin cancer. She holds a Master of Medicine in Skin Cancer from The University of Queensland and is accredited with the Skin Cancer College Australasia. Dr Danika is passionate about early detection, prevention, and providing evidence-based care for her patients.