Korean Sunscreen PA Ratings, Explained: What PA+ to PA++++ Measure, and Why PA++++ Is a Floor, Not a Score

Two labels, two kinds of light

SPF describes protection against UVB, the wavelengths that cause sunburn. UVA penetrates deeper, contributes to tanning and photoaging, and does not redden skin the way UVB does. The PA grade was created to give UVA protection its own label, which is why a sunscreen can show a high SPF and a modest PA grade at the same time.

How the PA grade is measured

The test is built on persistent pigment darkening (PPD), a lasting tan-like response that appears when skin is exposed to UVA. Volunteers are exposed on unprotected skin and on skin covered with sunscreen applied at a set dose. The protection factor is the UVA dose needed to produce a minimal darkening on protected skin divided by the dose needed on unprotected skin. The in-vivo method is described in the ISO 24442 standard, which was revised in 2022.

What the plus signs stand for

Korea's drug and cosmetics regulator, the MFDS, ties each grade to the measured UVA protection factor (PFA):

• PA+ means a PFA of 2 to under 4
• PA++ means 4 to under 8
• PA+++ means 8 to under 16
• PA++++ means 16 or more

Why PA++++ is a ceiling label, not a ranking

The top grade begins at 16 and has no upper bound. A product measured at 17 and one measured at 40 both print four plus signs, so the label cannot tell them apart. The grade is also a threshold bucket: a result just under 16 prints three plus signs. Treat the plus signs as a minimum, not a precise score.

SPF and PA are not interchangeable

A high SPF does not guarantee a high PA, and the reverse is also true. A broad-spectrum claim elsewhere uses different yardsticks: the EU recommendation asks that the UVA protection factor be at least one third of the labeled SPF, with a critical wavelength of 370 nm. These are separate regulatory tests, so a PA grade and a "broad spectrum" label are not the same statement. Our zinc oxide versus organic filters guide covers which filters cover UVA.

What the label does not tell you

Both numbers come from a lab dose of 2 mg per square centimeter. Most people apply less, and the protection they get drops with it. The 2 mg/cm2 guide explains the dose and the two-finger rule. Sweat, rubbing, and reapplication matter too, and a PA grade says nothing about them.

Reading a Korean sunscreen label

Look for both numbers, and treat SPF 30 or above with PA+++ or PA++++ as a sensible reading of the labels, not a guarantee of results. Look for the actual filters in the ingredient list, and check how the texture applies, since a product you will not apply generously protects less. If you are sorting through ingredients, the reapplying sunscreen over makeup guide covers the midday problem.

This article summarizes published standards and is not medical advice. Patch test any new product first, and ask a dermatologist about skin that reacts to sunscreen or about sun damage.