SPF vs PA+++ factor, is there a difference? and which is the better measure of sun protection

 We all know what SPF is and the importance of wearing sunscreen right? right? If you are on the fence (I am looking at you dark-skinned people) you need to read my extensive post on the importance of sun protection here.

When it comes to skincare, Korean skincare is the deep end of the pool and their approach to sun protection is no different.  Korean beauty culture prizes smooth even dewy skin which has influenced their innovation with sunscreen formulas. With the increasing popularity of Korean skincare products particularly sunscreen it is important to understand the different UV protection labels used to measure sun protection and how it differs from SPF.

To get started here is a summary on how exposure to UVA and UVB rays is damaging to your skin in different ways.


UVA rays penetrate deep into the skin causing wrinkles and other signs of premature ageing without any physical signs


UVB rays, on the other hand, affect the superficial layer of the skin causing burning

How Sunscreen Works

To understand the rating systems used on your favourite products, it’s important to understand how sunscreen protects your skin.

Sunscreen rating systems

There are two systems used to measure sunscreen protection against UV rays. Sun protection factor (SPF) is the most frequently used to measure sun protection in North America and Europe. The second less popular system is the PA system based on the persistent pigmentation darkening test (PPD test)used in Asia.

Sun Protection Factor (SPF )

This is the most common rating system and measures how well your skin is protected from UVB rays. On average, it takes 10-20 minutes after exposure to sunlight for the skin to burn. This means that a product which with an SPF of 15 will keep your skin from burning 15 times longer than without sun protection which translates to 150 -300 minutes of protection. Hence the reasons you need to reapply your sunscreen.

SPF vs PA+
SPF 50 protects from UVB and broad-spectrum means it protects from UVA

Broad Spectrum SPFs, on the other hand, protect you from both UVA and UVB rays so look for a broad-spectrum sunscreen.

A sunscreen with an SPF 15 blocks about 94 per cent of the UV, SPF 30 products block about 97 per cent of such rays, and SPF 45 sunscreen shields against about 98 per cent of rays so those that have much higher numbers are not really providing much extra.

PA ++

Korean sunscreens use a different rating system from the SPF number called the PA system which measures the level of protection from UVA rays. The greater the number of plusses after the PA, the more protection you get from UVA exposure. This rating is based on the PPD  test, or the persistent pigmentation darkening test and measures how much exposure to UVA rays your skin can tolerate without darkening.  The PPD values are not standardized system across all countries and vary depending on the region.

The results from PPD are converted to the PA system with a range from PA+(one +)  to PA++++( four +).  The maximum PA rating has a PPD value of 16 and means that you can withstand at least 16 times more UVA radiation before tanning. Since UVA rays do not show visible damage, they penetrate deeply into the skin.


This is what each PA rating means:

PA+ = Some UVA protection.

PA++ = Moderate UVA protection.

PA+++ = High UVA protection.

PA++++ = Extremely High UVA protection.

If a product’s PPD = 16 or higher, PA = PA++++, when shopping for sunscreen the greater the number of plus signs on your product the better protection it provides.

Challenges of the PA system

Although the PA system works it has some drawbacks when compared to SPF. First is that there is no agreement on how the PA values are achieved since it measures UVA rays darkening the skin which is not uniform.

Not all skin turns brown from sun exposure, or at the same rate which means the rating is inconsistent. It is also difficult to determine the difference in sun protection between a PPD of 20 and PPD of 40 which would both be rated as PA+++ or PA++++.

Why Korean sunscreens are better

  1. Korean sunscreen has a great texture which is important when you need to layer products and unlike regular sunscreen, Korean sunscreens are light, and easily spreadable.
  2. They incorporate other skincare benefits like hydration, antioxidants and skin tone-evening ingredients.
  3. They use newer and innovative ingredients unlike western sunscreens have not incorporated new ingredients since the 90s.
  4. Their formulas have more “photostability, larger molecular size which reduces skin penetration(less irritation ) and a broader absorption spectrum

Which is a better measure of sun protection SPF or PA +?

SPF testing is regarded as more scientific and easily replicated. While PA + factor is more subjective, however, if you are looking for a product that gives you the greatest bang for your buck you can’t go wrong with a Korean sunscreen. So although the process of testing for PPD is variable evidence shows that they are effective and as long as you use one with a high PA + factor you are good.

Have you ever wondered about the difference in the measurements between SPF and PA + let me know in the comments?

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  1. Melissa
    2022-02-13 / 4:47 am

    Hi I just wanted to add that PA system started as a domestic regulation system within Japan back in 1996! The ranking and categorization are still done by the organization there!

    • 2022-02-14 / 8:58 am

      Hi Melissa thank you for that wonderful addition. Its fantastic to know that the organisation still exists and is active

  2. 2024-04-20 / 6:03 pm

    Sunscreen is a very essential product for our skin. It protects our screen from sunburn. We should use Best Sunscreen which one is suitable for our skin.

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