What is SPF50? Which SPF is best?

SPF (Sun Protection Factor) is the measurement of a sunscreen’s ability to protect your skin from harmful UV rays. There are three types of UV rays emitted by the sun - UVA, UVB, and UVC. 

UVA rays contribute to skin damage that results in tanning, premature ageing and wrinkles. On the other hand, UVB rays cause sunburn and increases  the chances of skin cancer.

1. Understanding SPF and PA Numbers

The number following the SPF shows the relative time it takes for unprotected skin to begin reddening versus the time it takes for skin with sunscreen applied to start showing signs of redness. The SPF number on sunscreen labels primarily indicates the degree of protection against UVB rays.
Very loosely put, UVA = aging, UVB = burning.


The PA system number is used to denote the sunscreen’s protection factor against UVA rays. If you want to protect your skin from the aging and burning effects that exposure to the sun will cause, you will need to look for a sunscreen that has an SPF as well as a PA number, or one that has a “broad spectrum” on the product. 

In the UK, Boots created the star rating which measures the percentage of UVA radiation that’s absorbed by a product compared to UVB.

2. The Science Behind SPF50 Sunscreen

SPF50 sunscreen protects your skin by absorbing or reflecting the UVB rays from the sun. Many sunscreens include organic chemical compounds designed to absorb UV radiation. When you apply these sunscreens, these chemicals react to disperse UV radiation as heat. These types of sunscreens are often called chemical sunscreens.

On the other hand, some sunscreens contain inorganic components like zinc oxide or titanium dioxide. Sunscreens primarily composed of these ingredients are known as physical or mineral sunscreens. These components work by reflecting and scattering UV radiation away from your skin.

The level of SPF you apply decides how much UV rays get blocked:

  • SPF15 stops 93% of UVB rays
  • SPF30 stops 96.7% of UVB rays
  • SPF50 stops 98% of UVB rays
  • SPF100 stops 99% of UVB rays

But UVB rays can never be stopped completely which is why it is important to put on sunscreen again every two hours to keep your skin protected. To ensure comprehensive protection, you should choose SPF50 sunscreens labeled as broad spectrum as it signifies their ability to shield against UVA and UVB rays. 

By incorporating these factors into your sunscreen choices, you can mitigate the harmful effects of sun exposure, maintaining healthy and youthful-looking skin for years.

3. Benefits of Using SPF50 Sunscreen

SPF50 sunscreen offers many benefits that include preventing sunburn and reducing the risk of skin cancer and premature ageing. 

  1. Prevents Skin Damage:

    Sunburn is a sign of significant skin damage caused by excessive exposure to UV radiation. SPF50 sunscreen provides a high level of protection against UVB rays, the primary source of sunburn. SPF50 sunscreen shields your skin from these rays to prevent sunburn and minimise the associated discomfort.
  2. Reduces the Risk of Skin Cancer:

    Prolonged exposure to UV radiation is a leading cause of various types of skin cancer, including melanoma, squamous cell carcinoma, and basal cell carcinoma. SPF50 sunscreen blocks a significant percentage of UVB rays to reduce the cumulative damage to the skin cells and lower the risk of developing skin cancer.
  3. Slows the Process of Ageing:

    UV radiation accelerates ageing by breaking down collagen in the skin which leads to the loss of elasticity, formation of wrinkles, and uneven pigmentation. By providing comprehensive protection against UVB rays, SPF50 sunscreen helps preserve the skin's youthful appearance and prevents the formation of fine lines, wrinkles, and age spots.

      No matter the skin type, SPF50 sunscreen is beneficial for everyone. Whether you have sensitive, dry, or mature skin that needs protection, SPF50 sunscreen can help keep your skin safe from the sun's harmful effects. So, you should include SPF50 sunscreen in your daily skincare routine to keep your skin healthy and protected.

      4. Choosing the Right SPF Sunscreen

      When it comes to choosing the right SPF sunscreen, there are a few important factors to consider to ensure you are properly protected from the sun's harmful rays. 

      1. Skin Type: First, take into account your skin type. If you have oily or acne-prone skin, you may prefer a lightweight formula that will not clog pores. On the other hand,  if you have dry skin you should go for a moisturising sunscreen with soothing ingredients like aloe vera or hyaluronic acid. If you have sensitive skin, fragrance-free sunscreens are ideal to avoid any potential irritation.
      2. Skin Colour: Contrary to popular belief, your skin colour does not affect the level of SPF sunscreen you need. A person with a lighter skin colour needs to apply sunscreen more frequently than one with a darker skin tone, as on average, melanin gives an SPF of around 13, but this is not enough to offer adequate protection against sun damage.
      3. Broad Spectrum: Look for a broad spectrum sunscreen as it protects you against UVA and UVB rays for complete protection against sunburn, premature ageing, and skin cancer.
      4. Age Group: For children, sunscreens that are specifically formulated for their delicate skin, with gentle, hypoallergenic ingredients are the best.
      5. Facial or Full-body Coverage: If you are looking for face-specific formulations, you can explore sunscreens designed for use on the face only. Typically, face-specific sunscreens have lighter textures and may contain additional skincare benefits like antioxidants and moisturising ingredients.

            If you have any kind of skin condition, you must consult your doctor for advice to select the right SPF sunscreen for you. By considering all these factors, you can choose the perfect SPF sunscreen to keep your skin protected and healthy in the sun.

            5. What is the Difference Between SPF30 and SPF50 Sunscreens?

            The major difference between them is that SPF30 sunscreen blocks about 96.7% of UVB rays whereas SPF50 sunscreen blocks about 98% of UVB rays.

            It may seem marginal upon first look, but SPF30 allows 50% more UVB radiation exposure to the skin than SPF50.  With this knowledge, you can easily see why choosing an SPF50 sunscreen over an SPF30 one is the right option to prevent sun-induced damage. 

            6. How to Apply SPF50 Sunscreen

            To apply SPF50 sunscreen effectively and ensure maximum protection, it is essential to follow these best practices: First, you have to measure out a sufficient amount of sunscreen to cover your face and exposed areas of your body. 

            For the face:  The general rule is to use about two finger lengths of sunscreen, ensuring coverage from the forehead down to the chin. Additionally, allocate another finger length to cover the neck and ears. You can apply sunscreen to the tops of the ears and the tip of the nose for complete facial protection as well.

            For full body coverage: The amount of SPF sunscreen you need to apply varies based on age. For instance, children under 3 years require a minimum of 5 to 10 ml of sunscreen. On the other hand, children that are 3 to 5 years old need at least 10 to 15 ml. In addition, children aged 5 to 10 should use 15 to 20 ml of sunscreen. Adults need a minimum of 30 ml for complete body application.

            It is a good practice to apply SPF sunscreen 20 to 30 minutes before you have to leave the house as this will give your skin ample time to absorb it. In addition to this, reapplying SPF sunscreen is also very important to keep your skin protected whenever you are going out in the sun.

            7. How Long Will SPF50 Sunscreen Last & How Often Should I Reapply It?

            SPF50 sunscreen offers protection against the harmful UVB rays from the sun, typically lasting for about 50 times as long as your skin would naturally protect itself. However, it is important to keep in mind that factors such as sweat, water, and time can diminish its effectiveness. 

            To maintain adequate protection, it is recommended to reapply SPF50 sunscreen every two hours, especially if you are spending an extended period outdoors or participating in water activities. 

            Therefore, it is wise to keep a travel-sized sunscreen with you for convenient reapplication throughout the day. If you are wearing makeup, you can keep on hand a sunscreen stick or apply sunscreen with a sponge for hassle-free touch-ups on the go.

            9. What is the Best SPF50 Sunscreen for the Face?

            The perfect SPF50 sunscreen for your face is one that offers a non-sticky and light feel, easy application, and minimum build-up when reapplied. Nowadays, you can easily find light alternatives to the old-school thick creams. 

            Some of the crowd-favourite broad spectrum SPF50 sunscreens that provide light coverage and high protection are as follows:

            Purito Daily Soft Touch

            If you have sensitive skin, try Purito as it is gentle on the skin while providing high protection.


            Canmake Mermaid Gel

            If you are looking for an SPF50 that you can wear under makeup, Canmake is an excellent choice.


            Beauty of Joseon Matte Sun Stick

            If you need sunscreen to wear on the go, Beauty of Joseon can meet all your needs.

            Bioré UV Aqua Rich

            If you want a sunscreen that provides comprehensive protection while exercising outdoors, choosing  Biore UV is the best option.

             10. Will I Tan With SPF50?

            It is crucial to understand that tanning is a sign of DNA damage caused by prolonged exposure to UV rays and it increases the risk of skin cancer and premature ageing. SPF50 sunscreen helps you avoid tanning by blocking a significant percentage of UV radiation.

            It is essential to prioritise sun protection by wearing sunscreen daily, seeking shade during peak sun hours, and avoiding sunbeds altogether. You can opt for sunless tanning products if you desire a bronzed glow so that you can avoid the associated risks of UV exposure because protecting your skin from the sun's harmful rays is essential for maintaining healthy and radiant skin for years to come.

            11.  Is SPF50 Sunscreen Water-resistant?

            Some SPF50 sunscreens are water-resistant but none are water-proof. The US Food and Drug Administration (FDA) categorizes water-resistant sunscreens based on how long the sunscreen retains its stated SPF level in the water. If the sunscreen is water-resistant, it maintains its effectiveness for up to 40 minutes of water exposure.

            12. Does SPF50 Sunscreen Expire?

            Yes, SPF sunscreens do expire and you should be aware of that. Even if a sunscreen product does not have an expiry date on it, you should discontinue its use 12 months after opening the product.  But if you have not opened the sunscreen product then it should remain potent and usable for 3 years.

            13. Should I Use SPF50 on a Cloudy Day?

            UV rays from the sun can penetrate clouds and glass easily and cause skin damage even on sunless days. So, it is a good practice to wear your SPF50 sunscreen 365 days a year for comprehensive protection.

            14. Can I Use SPF on Sunbeds?

            Yes, you can use SPF on sunbeds but I would never recommend using a sunbed because they cause a lot of damage to your skin in the form of sunburn, hyperpigmentation, and more

            15. Environmental Considerations

            When considering the environmental impact of sunscreen, you could be mindful of certain ingredients that may pose risks to coral reefs and marine life. Studies have shown that ingredients like oxybenzone and octinoxate, commonly found in sunscreens, can contribute to coral bleaching and harm marine ecosystems in very large quantities. Consequently, these ingredients have been banned in regions like Hawaii to protect coral reefs.

            In response to growing concerns, some sunscreens are labelled as ‘reef safe’ which indicates that they do not contain harmful ingredients. However, it is crucial to note that the term reef safe can be misleading, as it may not account for other potentially harmful ingredients or the overall environmental impact of a product.

            Mineral-based sunscreens containing ingredients like titanium dioxide and zinc oxide are often considered safer alternatives for coral reefs. However, even these mineral ingredients may have drawbacks, such as the production of hydrogen peroxide, which can harm marine life.

            In navigating the complexities of environmental considerations in sunscreen usage, you should remain informed and critically evaluate product claims. You can seek out SPF sunscreen products from reputable sources like Perdita’s Skincare Store. In this way, you can ensure that the choices you make align with your values of environmental sustainability. 


            Understanding the significance of SPF50 sunscreen is important for maintaining healthy and protected skin. SPF50 sunscreens protect against sunburn and reduce the risk of skin cancer and premature ageing caused by UV radiation. 

            By incorporating SPF50 sunscreen into your daily skincare routine, you can shield your skin from the harmful effects of sun exposure and ensure it remains youthful and radiant for years. Choosing a suitable SPF50 sunscreen tailored to your skin type, preferences, and environmental considerations is essential for comprehensive protection. 

            Whether you opt for mineral-based formulations or reef-safe options, selecting a high-quality SPF50 sunscreen from our collection will help you preserve your skin's health and vitality. Visit Perdita’s Skincare Store and find the sunscreen best suited to the needs of your skin online conveniently.


            Back to blog

            Leave a comment

            Please note, comments need to be approved before they are published.