· By Mask Marie
SPF, PA++++, UVA & UVB: Understanding Korean Sun Care
What those numbers on your sunscreen actually mean — and why the PA system tells you something SPF alone never could.
Pick up almost any Korean sunscreen and you'll see two ratings on the front: an SPF number and a PA++++. Most of us know that higher SPF is better — but what does PA mean? And why does it matter as much, if not more, than SPF? If you've ever squinted at a label and moved on, this one's for you.
Sun protection is one of the most researched areas of skincare, and Korean brands have leaned into that research heavily — both in how they measure protection and in how they formulate for daily wearability. Understanding the rating system is the first step to knowing what you're actually putting on your skin and why.
UVA vs. UVB: Two Different Threats
Sunlight reaches us as a spectrum of ultraviolet (UV) radiation. For skin protection purposes, two bands matter: UVA and UVB. They behave very differently, and a good sunscreen needs to address both.
UVC (100–280nm): Absorbed almost entirely by the ozone layer. Not a meaningful concern for skin protection.
UVB (280–315nm): Causes sunburn. Affects the skin's surface. SPF directly measures protection against UVB. Intensity varies with season and time of day.
UVA (315–400nm): Penetrates deep into the dermis. Drives photoaging. Present year-round, all day, through glass and clouds. PA++++ measures protection here.
UVB: The Burn Ray
UVB radiation causes sunburn by damaging the DNA in surface skin cells. It's higher energy and its intensity fluctuates — strongest between 10am and 4pm, reduced in winter and on overcast days. Protecting against UVB is what SPF measures, and it's the primary focus of most Western sunscreen testing.
UVA: The Aging Ray
UVA accounts for roughly 95% of the UV radiation that reaches Earth's surface. Unlike UVB, it penetrates all the way down to the dermis — the deep structural layer where collagen and elastin live — and it's linked to photoaging: dark spots, loss of firmness, and fine lines that accumulate over years. UVA intensity stays relatively stable throughout the day and throughout the year, and it passes through glass. That means everyday exposure — commuting, sitting by a window, running errands — adds up over time in ways most people don't account for.
GOOD TO KNOW: Why "Year-Round" Sun Protection Matters.
While UVB is the more seasonally variable ray, UVA maintains consistent levels across all seasons and weather conditions. Research suggests that long-term cumulative UVA exposure is a significant driver of visible skin aging, which is why dermatologists recommend daily sunscreen use regardless of season or whether you plan to spend time outdoors.
Korean skincare culture has long incorporated daily SPF as a routine step rather than a seasonal one. That expectation shaped how Korean brands approached formulation: if people are going to apply it every single morning, it has to be comfortable to use. The result is a wide range of textures designed for daily wearability, not just occasional beach trips.
The key point: protecting against UVB and UVA requires different measurements. SPF tells you about UVB coverage. To understand your UVA protection, you need the PA system.
What SPF Actually Measures
SPF stands for Sun Protection Factor. It measures how well a sunscreen protects against UVB radiation, expressed as a multiplier of your skin's natural tolerance. If your unprotected skin would begin to redden after 10 minutes in the sun, SPF 50 theoretically extends that threshold to 500 minutes.
In practice, SPF is better understood as a fraction of UVB rays blocked:
- SPF 30 blocks approximately 97% of UVB rays
- SPF 50 blocks approximately 98% of UVB rays
- SPF 50+ blocks approximately 98.5% or more
The jump from SPF 30 to SPF 50 sounds small in percentage terms, but it makes a meaningful practical difference — because SPF ratings are determined in controlled lab conditions using a specific amount of product. In everyday use, most people apply roughly 25–50% of that amount, which proportionally reduces the delivered protection. Higher SPF builds in a real-world safety margin.
A note on SPF testing: Lab conditions assume a precise, even application of 2mg per cm² of skin. In practice, application is rarely that uniform. This is one reason dermatologists generally recommend SPF 50 for daily face use — not because SPF 30 is inadequate, but because it accounts for how sunscreen actually gets applied in the real world.
Most Korean sunscreens target SPF 50 or SPF 50+ as their standard. It's also worth remembering that SPF only tells you about UVB protection — which is exactly why the PA rating exists alongside it.
PA++++: The UVA Rating You Need to Understand
The PA system (Protection Grade of UVA) originated in Japan and is the standard UVA rating across much of Asia, including Korea. It fills a gap that SPF alone doesn't — giving consumers a meaningful, standardised way to compare UVA protection between products.
PA ratings are derived from the PPD (Persistent Pigment Darkening) test, which measures how well a sunscreen protects against UVA-induced skin darkening. The more plus signs, the higher the protection factor:
PA+ — Some UVA protection. PPD factor of 2–4. A starting point, but limited for extended sun exposure or regular daily use.
PA++ — Moderate UVA protection. PPD factor of 4–8. Suitable for low-intensity sun exposure with minimal time outdoors.
PA+++ — High UVA protection. PPD factor of 8–16. A solid choice for daily wear and outdoor activities.
PA++++ — Very high UVA protection. PPD factor of 16 or above. The highest level on the PA scale, and the benchmark for most Korean daily sunscreens.
The combination of SPF 50 + PA++++ means a sunscreen has been tested to offer high protection across both UVB and UVA — which is what you need for genuine broad-spectrum coverage. Most products in our collection carry both ratings.
What about the US "broad spectrum" label? In the US, sunscreens labelled "broad spectrum" have passed the FDA's Critical Wavelength test, which confirms some degree of UVA coverage. However, the FDA doesn't require the PA scale or a specific UVA protection rating on labels, so "broad spectrum" gives you less granular information than PA++++ does. Neither system is inherently superior — they're just different frameworks for communicating UVA coverage to consumers.
SPF tells you one part of the story. PA tells you the other. You need both numbers to understand what a sunscreen is actually doing.
Why Korean Sunscreens Feel Different to Use
The science of UV protection is fairly universal — what sets Korean sun care apart in practice is its formulation philosophy. Because sunscreen is treated as a daily skincare step in Korean culture rather than a seasonal product, brands have invested heavily in making formulas genuinely enjoyable to wear. The logic is straightforward: a sunscreen that feels good to apply is one you'll actually use consistently. And consistency is the entire point.
The result is a wider range of textures than you'd typically find in Western sun care — watery serums, gel-creams, lightweight lotions, cushion sticks — designed to wear comfortably under makeup and on bare skin alike. Korean sun care products also commonly include skincare-active ingredients alongside the UV filters: centella asiatica for soothing, niacinamide for brightening, hyaluronic acid for hydration, fermented extracts for barrier support. The sunscreen becomes part of the routine rather than something layered reluctantly on top of it.
This doesn't mean Korean sunscreens are inherently "better" in any absolute sense. What it does mean is they're formulated with daily use as the goal — which has real implications for how consistently people reach for them.
Korean Sunscreens Worth Knowing
Here are the sunscreens we carry at Mask Marie, with notes on what each one does well and who it tends to suit.
Beauty of Joseon Relief Sun: Rice & Probiotics Sun Cream — SPF 50 PA++++ A widely used daily sunscreen formulated with fermented rice and probiotics alongside its UV filters. Lightweight texture, no white cast, and sits comfortably under makeup. A good starting point if you're new to Korean SPF. Shop Now
Beauty of Joseon Relief Sun: Aqua-fresh Rice + B5 Sun Cream — SPF 50 PA++++ An updated version of the Relief Sun formula with Vitamin B5 added for extra hydration. The texture is slightly more aqueous and feels particularly comfortable on dry or combination skin. A straightforward, reliable daily option. Shop Now
Beauty of Joseon Matte Sun Stick: Mugwort & Camelia — SPF 50 PA++++ A solid-format sun stick that works well for touch-ups throughout the day, including over makeup. The matte finish makes it popular with oily and combination skin types. Convenient to carry and easy to reapply. Shop Now
SKIN1004 Madagascar Centella Hyalu-Cica Water-Fit Sun Serum — SPF 50 PA++++ A serum-textured sunscreen with centella asiatica and hyaluronic acid. The watery consistency is a good option if traditional sunscreen textures feel heavy. Absorbs quickly and layers well. Particularly suited to sensitive or reactive skin. Shop Now
TIRTIR Hydro UV Shield Sunscreen — SPF 50 PA++++ A hydrating daily sunscreen with a clean, non-greasy finish. Applies evenly, doesn't pill under makeup, and is comfortable for extended wear. One of the more accessible price points in the collection for what it delivers. Shop Now
TIRTIR Off the Sun Air Mousse — SPF 50 PA++++ A mousse-textured SPF that's noticeably different to apply — airy and light, it melts in quickly and doesn't sit heavily on skin. If reapplication is something you tend to skip, the texture here makes it considerably more approachable. Shop Now
Goodal Green Tangerine Vita-C Dark Spot Care Sun Serum — SPF 50 PA++++ Combines SPF 50 PA++++ protection with Vitamin C — worth considering for anyone dealing with hyperpigmentation or uneven skin tone. Sun protection prevents new spots from forming; Vitamin C helps address existing discoloration. A practical combination in one step. Shop Now
Roundlab Birch Juice Moisturizing UV Lock Sunscreen — SPF 50 PA++++ Well-rated on Korean beauty platforms for its hydrating, comfortable wear. Birch juice is a lightweight humectant that keeps the formula from feeling dry or tight. Works across skin types and holds up consistently as an everyday option. Shop Now
Centellian 24 Madeca Derma Shield Mild Sun Cream — SPF 50 PA++++ Formulated with Madecassoside, a compound derived from centella asiatica, this is a considered option for sensitised or easily irritated skin. Focused on minimising irritation alongside solid UV coverage — a reasonable choice for barrier recovery or post-treatment routines. Shop Now
Rejuran UV Protection Sun Cream — SPF 50+ PA+++ Rejuran's sunscreen incorporates PDRN (Polydeoxyribonucleotide) alongside its UV filters. Note the PA+++ rating rather than PA++++ — still high UVA coverage, and a natural fit if you're already using other Rejuran products in your routine. Shop Now
Matching a Sunscreen to Your Skin Type
The most effective sunscreen is the one you'll actually apply — and reapply — consistently. Texture and finish matter more than people give them credit for, because an uncomfortable formula is one you'll use less of or apply less often.
Oily / Acne-Prone: Look for gel textures, matte or satin finishes, and lightweight water-based formulas. Sun sticks are useful for reapplication without adding grease. Consider: Beauty of Joseon Matte Sun Stick, TIRTIR Hydro UV Shield.
Dry / Sensitive: Prioritise formulas with hydrating or barrier-supportive ingredients — Vitamin B5, centella, ceramides. A formula that doubles as moisture saves a step. Consider: Beauty of Joseon Relief Sun Aqua-fresh, Centellian 24 Madeca Derma Shield.
Dark Spots / Pigmentation: Consistent sun protection is one of the most reliable tools for preventing new hyperpigmentation. A formula with Vitamin C addresses both prevention and brightening at once. Consider: Goodal Green Tangerine Vita-C Dark Spot Care Sun Serum.
Application Guide: Getting the Most Out of Your Sunscreen
01 — Use enough. The standard tested amount is approximately ¼ teaspoon for the face alone. Most people apply significantly less, which proportionally reduces the protection delivered.
02 — Apply as the last step of your morning skincare routine, after moisturiser and before makeup. This ensures the UV filters sit correctly on the skin surface rather than being disrupted by subsequent layers.
03 — Reapply every 2 hours when outdoors. UV filters degrade with sun exposure, sweat, and physical contact. Sun sticks and lightweight formulas make this more practical throughout the day.
04 — Wear it daily, not just in summer. UVA is present at meaningful levels year-round, including on overcast days and indoors near windows. Daily application is more protective than seasonal use.
05 — Remove it properly at night. An oil cleanser or cleansing balm will break down sunscreen more thoroughly than a water-based cleanser alone — which matters for keeping your skin barrier in good shape.
The Short Version
SPF measures UVB protection — the rays that burn. PA++++ measures UVA protection — the rays that contribute to long-term skin aging. You need both for genuinely broad-spectrum coverage, and the PA system gives you more detailed UVA information than most Western labelling does.
Korean sun care products tend to be formulated with daily, year-round use as the goal, which generally produces lighter, more wearable textures alongside the protective actives. Whether you're drawn to the SPF 50 PA++++ ratings, the skincare ingredients, or simply the fact that these actually feel good to use — any of those are solid reasons to make sunscreen a consistent part of your morning routine.
If you have questions about any of the products in our collection, we're always happy to help you find a good fit for your skin.