If you search for Round Lab sunscreen in the U.S., you may notice something confusing.
The product on Round Lab’s official U.S. store is called Birch Moisturizing Sunscreen UVLock SPF 45+ Broad Spectrum.
But the Round Lab sunscreen sold in Korea is labeled Birch Juice Moisturizing Sunscreen SPF50+/PA++++.
The packaging looks familiar, both belong to the Birch line, and both are positioned as lightweight daily sunscreens. But they are not simply the same sunscreen with a different SPF number printed on the front.
The U.S. and Korean versions use different labeling systems and different UV-filter combinations.
Round Lab US vs. Korea at a glance
| U.S. version | Korean version | |
|---|---|---|
| Product name | Birch Moisturizing Sunscreen UVLock | Birch Juice Moisturizing Sunscreen |
| SPF label | SPF 45+ | SPF50+ |
| UVA label | Broad Spectrum | PA++++ |
| Size | 50ml | 50ml |
| Market | United States | Korea |
| Key UV filters | Avobenzone, Homosalate, Octisalate | Uvinul A Plus, Uvinul T 150, Tinosorb M, Uvasorb HEB |
The important difference is not the five-point gap between SPF 45+ and SPF50+.
It is the formula underneath.
The U.S. Round Lab sunscreen uses a different UV-filter system
Round Lab’s official U.S. website currently lists Birch Moisturizing Sunscreen UVLock SPF 45+ Broad Spectrum as a 50ml sunscreen for the U.S. market.
Its active UV filters include:
- Avobenzone
- Homosalate
- Octisalate
The formula also contains skincare ingredients associated with the Birch line, including birch juice, niacinamide, hyaluronic acid, glycerin and allantoin.
So this is still recognizably a Round Lab Birch sunscreen. But its sunscreen-filter system is not the same as the Korean product.
That distinction matters because sunscreen is regulated differently in the United States, where it is treated as an over-the-counter drug and must follow FDA requirements for active ingredients and labeling.
The Korean version uses a different set of filters
The Korean-market Round Lab Birch Juice Moisturizing Sunscreen is labeled SPF50+/PA++++.
Current Korean retail ingredient listings for the product show a different UV-filter combination:
- Diethylamino Hydroxybenzoyl Hexyl Benzoate — Uvinul A Plus
- Ethylhexyl Triazone — Uvinul T 150
- Methylene Bis-Benzotriazolyl Tetramethylbutylphenol — Tinosorb M
- Diethylhexyl Butamido Triazone — Uvasorb HEB
The same UV-filter combination appears consistently across the Korean retail listings I checked.
Those Korean retail listings also identify Kolmar Korea as the manufacturer and Seorin Company as the responsible distributor, which is another useful detail to check when you are trying to confirm that you are looking at the Korean-market product.
The Korean formula also contains familiar skincare ingredients such as niacinamide, glycerin, birch juice, sodium hyaluronate, hyaluronic acid and allantoin.
So there is overlap on the moisturizing side of the formulas. The biggest difference is the UV-filter system.
That is why describing the U.S. product as simply “the American packaging of the Korean Round Lab sunscreen” would be misleading.
Why does the U.S. bottle say SPF 45+ Broad Spectrum instead of SPF50+/PA++++?
The labels make the difference look especially dramatic, but the two markets do not use exactly the same labeling system.
In Korea, sunscreens commonly display both SPF, which primarily reflects protection related to UVB, and PA, which communicates levels of UVA protection.
That is why the Korean Round Lab product is labeled:
SPF50+ / PA++++
The U.S. system instead uses an SPF value and, when a product passes the required UVA testing, the label Broad Spectrum.
The FDA explains that SPF mainly reflects protection against UVB-related sunburn, while Broad Spectrum indicates protection across both UVA and UVB wavelengths.
So the American label:
SPF 45+ Broad Spectrum
should not be read as a simple lower version of:
SPF50+/PA++++
They are labels produced under different regulatory systems.
The absence of PA++++ on the American product does not mean it has no UVA protection. Its Broad Spectrum designation is the relevant U.S. label.
Is SPF50+ automatically better than SPF45+?
No.
The numbers are visually obvious, but they are not the most useful way to compare these two products.
SPF is not a score where SPF50 is automatically meaningfully “better” than SPF45 for every user. The more important distinction here is that the two products are built around different filter systems and different market requirements.
So I would not choose the Korean version simply because 50+ looks higher than 45+.
The more useful question is:
Which formula are you actually trying to buy?
Does the Korean version have “better” UV filters?
This is where online comparisons can become too simplistic.
You may see the Korean formula described as superior because it uses filters that are common in Korean and European sunscreen formulations but are not used in the same way in the U.S. market.
That conclusion goes too far.
An ingredient list can tell us that the formulas are different. It cannot, by itself, prove that one finished sunscreen will perform better for every person or every situation.
It also does not tell you which texture your skin will tolerate better, which product will work better under makeup or which one you will actually use consistently.
The useful conclusion is not:
Korean = better.
It is:
Korean ≠ U.S.
What about texture and skincare ingredients?
This is where the two products are more closely related.
Round Lab positions the U.S. UVLock sunscreen as lightweight and moisturizing, and its formula still includes birch-derived ingredients and several humectants associated with the Birch line.
The Korean version is also positioned as a moisturizing daily sunscreen and contains birch juice, niacinamide and hydrating ingredients.
So the U.S. version is not an unrelated product with the Round Lab name placed on it.
The product concept is similar. The UV-filter system is not.
That is probably the simplest way to describe the relationship between them.
Which Round Lab sunscreen are you actually buying?
If you are shopping in the U.S., do not rely only on a listing that says “Round Lab Birch Sunscreen.”
Check three things:
- The exact product name
- The SPF/UVA label
- The ingredient list
If the package says:
Birch Moisturizing Sunscreen UVLock SPF 45+ Broad Spectrum
you are looking at the U.S.-market version discussed in this article.
If it says:
Birch Juice Moisturizing Sunscreen SPF50+/PA++++
you are looking at the Korean-market version.
This matters especially on marketplaces such as Amazon, where imported Korean stock and U.S.-market stock can appear in similar search results. A familiar birch-tree package is not enough to identify the formula.
If your goal is specifically to try the sunscreen sold in Korea, verify the SPF50+/PA++++ version, its ingredient list, and the Korean manufacturer/distributor information.
If you simply want the official Round Lab sunscreen formulated and distributed for the U.S. market, the SPF45+ Broad Spectrum UVLock version is the relevant product.
Those are two different purchasing decisions.
This is not unique to Round Lab
Round Lab is a useful example because the distinction is unusually easy to see: different SPF labeling, different UVA labeling and different ingredient lists.
But the broader issue applies beyond one brand.
K-beauty products do not always move from Korea to another country unchanged. Regulations, approved ingredients, claims and distribution requirements can affect what eventually appears on an overseas shelf.
I found the same broader pattern when comparing the Korean sunscreens that go viral overseas with what Korean beauty platforms actually rank. Some products genuinely succeed in both markets, but the version international shoppers encounter is not always a perfect copy of what Korean consumers see at home.
Regulation can change the picture further. My guide to exosomes in K-beauty looks at another example of why a Korean beauty trend cannot always be interpreted the same way once it crosses markets.
So which version should you buy?
I would choose based on which product you actually want, not on the assumption that one country automatically gets the superior version.
Choose the Korean SPF50+/PA++++ product if your goal is specifically to try the Korean-market Birch Juice sunscreen and its formula.
Choose the official U.S. UVLock SPF45+ Broad Spectrum product if you want the Round Lab sunscreen formulated and distributed for the U.S. market.
In either case, buy from a source where you can verify the exact version.
And if someone recommends “the Round Lab sunscreen,” there is one useful follow-up question:
Which one?