Posted by Amanda Hawtin
on April 10, 2026
Sunscreen is one of the most important daily defences against premature skin ageing and melanoma.
Daily exposure to UV radiation contributes to fine lines, wrinkles, pigmentation, and long-term skin damage. It is also one of the most significant risk factors for skin cancer.
As a qualified cosmetic chemist, this is the advice I give consistently: sunscreen is not about the brand. What truly matters is how much you apply and how often you reapply.
Understanding SPF
SPF measures protection against UVB rays, which cause sunburn and contribute to skin cancer. It does not measure UVA protection, which is responsible for deeper skin ageing and pigmentation.
While SPF numbers sound very different, the real-world difference between SPF 30 and SPF 50 is smaller than most people expect.
SPF 50 blocks approximately 98% of UVB rays; SPF 30 blocks around 96.7%; SPF 15 blocks about 93%.
Why Most People Are Not Getting the Protection They Think
Most people apply only half the recommended amount of sunscreen, meaning an SPF 50 often performs closer to a much lower level of protection in real-life use.
To achieve the protection stated on the label, sunscreen must be applied at approximately 2 mg per square centimetre of skin.
How Much Sunscreen Should You Apply?
In practical terms, this equals about half a teaspoon for the face and neck combined, or roughly one teaspoon for each arm and leg, and two teaspoons for the torso.
For the entire body, this is around 30 to 35 ml per full application, which is close to a standard shot glass amount.
Most people apply significantly less than this, which means the real protection on the skin is often much lower than the SPF listed on the label.
Applying a generous, even layer and reapplying every two hours helps ensure the sunscreen performs as intended.
Why Reapplication Matters
Sunscreen protection is not permanent throughout the day.
Once applied, the protective film on the skin can gradually break down due to sweating, touching the skin, natural oil production, and environmental exposure.
UV radiation is present continuously, and protection reduces over time if sunscreen is not reapplied.
Reapplication every two hours is essential, particularly when outdoors, sweating, swimming, or exposed to direct sunlight.
Choosing the Right Sunscreen
For everyday use, I personally prefer an SPF 30 because they are typically lighter, easier to apply, and I find myself applying them more generously and reapplying more often.
A generous application of SPF 30 may result in better coverage than a light application of SPF 50.
What is most important is choosing a sunscreen you are realistically going to apply, and reapply throughout the day.
The Truth About Sunscreen Brands
All sunscreens sold in Australia undergo rigorous testing, whether they are made locally or overseas. Australia has some of the highest sunscreen standards in the world.
Look for sunscreens that provide broad-spectrum protection against both UVA and UVB rays. UVA contributes to skin ageing and pigmentation; UVB causes sunburn and increases skin cancer risk.
Effective formulas often combine organic (chemical) UV filters, which absorb UV radiation, with mineral filters such as zinc oxide or titanium dioxide, which absorb and scatter UV radiation to help protect the skin.
Storage and Expiry
Sunscreen does not last forever. Expired sunscreen may not provide the level of protection stated on the label.
If it has expired, it is time to replace it.
Avoid storing sunscreen in hot cars or extreme heat. Prolonged exposure to high temperatures can reduce its effectiveness.
Daily Sun Protection as an Act of Care
Sun protection is essential every day.
UV rays that contribute to ageing and pigmentation are present all year, even on cloudy days. Make sunscreen the final step in your morning skincare ritual, 365 days a year.
Store sunscreen correctly. Heat and prolonged sunlight exposure can reduce SPF effectiveness, so keep sunscreen in a cool place such as your bathroom shelf or handbag rather than in a hot car.
Protect more than just your face. The neck, chest, and hands are often the first areas to show visible sun damage. Extending your daily SPF application to these areas supports better long-term skin health.
Keep sunscreen simple. The best sunscreen is the one you will use consistently. Choose a formula that feels comfortable on your skin and fits easily into your daily routine.
Daily sun protection is a quiet act of care for your future skin.
