Ultraviolet radiation has been categorised into two broad categories UVA and UVB.The SPF range you see in sunscreen bottles is what protects your skin from UVB radiation. There is still a debate on which UV rays are more dangerous. To simplify UV rays we understand them through wavelengths, while UVB has shorter wavelengths, it still holds higher photon energy which is why you notice the tanning and sunburns when exposed to sun. UVA has longer wavelengths and reaches your skin even on a cloudy day, this is where the problem arises. UVA is the primary concern for photoageing and penetrates deeper into the skin’s epidermis. This is where PPD in sunscreen enters the picture, it is a measure to test how well a sunscreen performs against UVA radiation. In this article we go further into this topic to help you understand the science behind sunscreens.
WHAT DOES THE PPD NUMBER ACTUALLY TELL YOU?
PPD stands for Persistent Pigment Darkening, which means it uses specific measures using numbers to measure how well a sunscreen protects your skin against UVA- induced pigmentation. UVA radiation has longer wavelengths and is what leads to photoageing, collagen damage, long term pigmentation and and tanning. PPD uses persistent pigmentation against UVA rays as the endpoint to understand. PPD is different from sunscreen because the SPF number in a sunscreen is what helps us understand the ability of a sunscreen to protect against UVB rays. (PubMed)
Note: 95% of the ultraviolet rays which reach the earth’s surface are UVA rays so be it a cloudy day or a day indoors it is UVA you should be concerned about. What helps is choosing a high PPD sunscreen, but PPD number is not mentioned on sunscreen bottles. This is where PA and the plus(+) symbol on sunscreen bottles start making more sense.
HOW IS PPD MEASURED?
The testing process itself is fairly methodical. A controlled UVA light source is used to expose small areas of skin, some protected by the sunscreen being tested, some left unprotected as a comparison baseline. Researchers then assess how much UVA exposure it takes to produce persistent pigment darkening in each area.
Central to this is a value called the Minimal Persistent Pigment Darkening Dose or MPPD, essentially the smallest amount of UVA exposure needed to trigger that visible pigment-darkening response in a given area of skin. The ratio between the MPPD on protected skin and the MPPD on unprotected skin is what generates the PPD or UVA protection factor, for that specific sunscreen.
WHAT IS THE DIFFERENCE BETWEEN PPD AND PA++++?
|
PPD |
PA |
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Uses persistent pigmentation as endpoint |
It’s a protection grade against UVA |
|
Numerical UVA protection factor |
Consumer-friendly UVA rating |
|
Based on UVA testing |
Derived from the PPD/UVA-PF framework used by the relevant system |
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Gives a number |
Uses + signs |
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More precise numerical information |
Easier to read on packaging |
To simplify it we can say that PPD is the actual laboratory measurement which is obtained during the testing of skin under different UVA conditions, whereas PA is a grading system(developed by Japan Cosmetic Industry Association) which is displayed on the sunscreen to have a clear understanding of how well a sunscreen performs under UVA radiation.
Note: PA translates that underlying numerical protection into a simpler category system: PA+ indicates lower UVA protection, PA++ moderate, PA+++ high and PA++++ very high. It's designed to be quick and legible on a product label, where a raw number might not communicate much to most shoppers standing in a store aisle.
WHAT DOES DIFFERENT PPD NUMBERS MEAN?
PPD is a methodological approach which uses different numbers ranging less than four (>4) to above forty (<40). Different PPD numbers represent the precise multiplier of UVA protection your skin receives compared to wearing no sunscreen at all.A PPD number tells you how many times more UVA radiation your protected skin can withstand before it begins to darken or tan (persistent pigment darkening).
Here is a table reference to understand different PPD values and their impact when compared beside PA gradings in practical everyday life:
|
PPD Value |
Level of UVA Protection |
PA Equivalent |
Suitable for |
|
PPD 2-3 |
Blocks minimal UVA rays (~50–66%). Skin takes 2–3x longer to tan. |
PA+ |
Basic indoor protection with minimal window exposure. |
|
PPD 4-7 |
Blocks moderate UVA rays (~75–85%). Skin takes 4–7x longer to tan. |
PA++ |
Short daily commutes, low-UV index days |
|
PPD 8-15 |
Blocks high levels of UVA rays (~87–93%). Skin takes 8–15x longer to tan. |
PA+++ |
Extended outdoor time, general daily sun protection |
|
PPD 16-29 |
Blocks very high levels of UVA rays (~93–96%). Skin takes 16–29x longer to tan. |
PA++++ |
Strong sun exposure, preventing photoageing, active outdoor sports |
|
PPD 30+ |
Extreme UVA filtration (>96%). Designed for maximum dermal protection |
PA++++ |
Hyperpigmentation/melasma prone skin, post-dermatological procedures, intense beach/tropical sun. |
IS A HIGHER PPD ALWAYS BETTER?
Higher UVA protection is generally a good thing, but the highest number on the shelf isn't automatically the only factor worth chasing. What matters just as much in practice is your actual UV exposure that day, whether you're dealing with brief daily exposure or a full day outdoors, whether the product offers genuine broad-spectrum protection rather than just a strong UVA number in isolation, how usable and comfortable the formula actually is and whether you're applying it consistently and reapplying when you need to.
DOES PPD TELL YOU HOW LONG SUNSCREEN WILL PROTECT YOU?
No and this is worth stating plainly because it's such a common misunderstanding. A PPD value shouldn't be interpreted as a fixed number of hours of protection, that's simply not what the test is designed to measure.
Real-world sunscreen performance depends on a lot of variables the lab test doesn't capture, how much product you actually applied, how evenly you spread that film across your skin, whether you've been sweating, whether you've gone swimming, whether you've rubbed or wiped your face during the day, your actual UV exposure in that specific environment and whether you've reapplied at appropriate intervals. PPD tells you something meaningful about relative UVA resistance under controlled conditions, it doesn't tell you when to reapply or how long you're covered for on a given afternoon.
IS PPD THE SAME AS UVA-PF?
Not exactly, though they're closely related. PPD refers to a specific UVA-testing approach and the value it generates, while UVA-PF, UVA Protection Factor, is a broader term used to describe UVA protection more generally, sometimes derived using the PPD method and sometimes using other testing approaches depending on the regulatory system involved.
This is part of why you might see different terminology used across different markets and product labels, it's not that brands are being inconsistent for no reason, different regions have historically used somewhat different frameworks to communicate UVA protection. It's worth not assuming every label uses these terms completely interchangeably, even when they're describing conceptually similar things.
SHOULD YOU LOOK FOR PPD OR PA++++?
If the exact UVA factor happens to be available on a product you're comparing, a numerical PPD or UVA-PF value can give you more granular information than a category alone.
If the packaging uses the PA system instead, which is far more common, PA++++ gives you a clear, easy consumer-facing signal of high UVA protection without needing to do any interpretation yourself.
For everyday sunscreen selection, it's also worth weighing broad-spectrum coverage overall, the SPF number, general UVA protection, how well the formula suits your specific skin and how comfortable and consistent you'll actually be using it day to day. Worth being clear, PPD isn't automatically "better" than PA++++, they're simply two different ways of communicating UVA protection, one more granular, one more consumer-friendly.
RECOMMENDED SUNSCREEN
DECONSTRUCT GEL SUNSCREEN
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Formulated with SPF 50 PA++++ which provides broad spectrum protection against both UVA and UVB radiation.
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Protects the skin against photoageing,collagen damage, tanning, pigmentation and sunburns
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Uses new-gen photostable UV filters MBBT, DHHB, BEMT and EHT and has better formulation which is more suitable for every skin type.
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Non-comedogenic and fragrance free formula making it suitable for everyday use for normal, oily and combination skin types
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Lightweight feel and non-greasy texture that does not leave the skin feeling tacky or oily upon layering and suitable for oily skin types as well.
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Does not leave behind any whitecast and settles down into a smooth and comfortable sunscreen on the skin
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Gentle and non-drying formula built around humectants using advanced science backed formulation
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Recommended by dermatologists and provides maximum PA protection, it is the perfect everyday sunscreen on the go.
Note : For anyone comparing UVA protection across products, the relevant published information here is the PA++++ rating itself, this article is meant to help you understand how a numerical PPD value works generally, not to assign one to a specific product that hasn't published it. For full product details, the Deconstruct Gel Sunscreen page covers the complete formulation and usage information.
PPD VS PA++++ AT A GLANCE
|
Question |
PPD |
PA Grading |
|
What does it indicate? |
Numerical UVA protection factor |
High UVA protection category |
|
Format |
Number (2-40+) |
Plus signs(+) |
|
Main purpose |
Quantitative UVA assessment |
Easier consumer communication |
|
Found on all sunscreen labels? |
No |
Common in Asian markets |
|
Is higher generally associated with stronger UVA protection? |
Yes |
More + signs indicate higher category |
FINAL THOUGHTS
To conclude we can say that PPD is a more laboratory based approach which is used in Vivo tested environments to measure how well a sunscreen provides protection against the UVA induced radiation. UVA holds longer wavelengths and tends to accumulate deeper into the skin and remain for longer duration and consists of 95% of the atmosphere’s UV radiation. Modern sunscreens use the Japanese Standard of PA grading system using + symbol to provide higher PPD protection. In this article we have explained the numbers of PPD against PA grading using tables. Put simply PPD acts like the CGPA while PA acts like the letter grade system. We recommend using The Deconstruct Gel Sunscreen which uses new gen filters and provides broad spectrum protection against both UVA and UVB radiation, a formulation backed by science and loved by many.
FREQUENTLY ASKED QUESTIONS
WHAT DOES PPD MEAN ON SUNSCREEN?
PPD stands for Persistent Pigment Darkening, a numerical measure of how much more UVA exposure protected skin can withstand compared to unprotected skin before showing the same pigment-darkening response, under standardized testing.
IS PPD THE SAME AS PA++++?
Not exactly. PPD is a numerical UVA protection factor, while PA++++ is a category-based rating derived from that same underlying UVA-testing framework, designed to be easier to read on packaging.
IS PA++++ EQUAL TO PPD 16?
PA++++ generally corresponds to the higher end of UVA protection associated with elevated PPD values, but exact numerical equivalence can vary depending on the specific testing standard and region involved.
IS A HIGHER PPD ALWAYS BETTER?
Higher UVA protection is generally beneficial, but broad-spectrum coverage, consistent application and product usability all matter just as much for real-world protection.
DOES PPD TELL YOU HOW MANY HOURS SUNSCREEN LASTS?
No. PPD reflects a laboratory comparison of UVA resistance, it doesn't indicate a specific duration of protection, real-world factors like application amount and reapplication determine that.
WHAT IS THE DIFFERENCE BETWEEN PPD AND UVA-PF?
PPD refers to a specific UVA-testing method and value, while UVA-PF is a broader term for UVA protection factor that can be derived through PPD or other testing approaches depending on the regulatory system.
