Sun Protection
Updated September 8, 2026
Round Lab's Birch sunscreen is worth considering if you want a moisturizing daily cream, but check the version before buying. The US UVLock SPF 45 and Korean SPF 50+ PA++++ use different sunscreen filters. A separate US SPF 50 label also exists, so the number alone won't tell you which formula you're getting.
Our view: the US SPF 45 makes sense to investigate for ordinary daily wear when you prefer a cream with some dewiness. It isn't the choice we'd make for swimming or a sweaty outdoor workout, because its directions tell you to use a water-resistant sunscreen for those activities. For the Korean version, make sure any texture review or ingredient list actually describes that tube.
This review compares current official product information, US Drug Facts labels and published editorial reviews, checked September 8, 2026. We haven't worn or independently tested these sunscreens. The aim is to help you choose accurately, without borrowing someone else's results.
The familiar birch trees appear across several products. Look below the illustration for the complete name and protection statement, then check the back of the tube or carton.
Round Lab's US shop currently lists Birch Moisturizing Sunscreen UVLock SPF 45 Broad Spectrum, in a 50 mL tube. Its page title still includes “45+” in places; the inspected package photograph and corresponding Drug Facts label state SPF 45. The photo at the top of this article shows that version. Current Round Lab US product.
The matching US label lists these sunscreen actives:
Those percentages belong to this label. Niacinamide, birch juice and hyaluronic acid appear among the other ingredients; they aren't additional declared sunscreen actives. This distinction matters because a website's “active ingredients” marketing section can include skincare ingredients alongside UV filters. SPF 45 Drug Facts.
The official Korean product page identifies 자작나무 수분 선크림, a 50 mL sunscreen whose displayed package says SPF 50+ PA++++. Its published ingredient panel includes four different UV filters: diethylamino hydroxybenzoyl hexyl benzoate, ethylhexyl triazone, methylene bis-benzotriazolyl tetramethylbutylphenol and diethylhexyl butamido triazone. Round Lab Korean product and label images.
You don't need to memorize those long names. Use them to check whether a retailer's ingredient list belongs with its product photograph. The Korean list should not be substituted for the US SPF 45's three-active Drug Facts panel.
Both formulas discussed here use chemical UV filters. A Birch product with “Mild-Up” in the name is another formula, as are the Sun Serum, cushion and stick. Their texture and protection claims need their own checks.
There is also a US Birch Juice Moisturizing UVLock Sunscreen SPF 50 Broad Spectrum label in DailyMed. It lists avobenzone 2.7%, homosalate 13.5% and octisalate 4.5%. Its existence does not establish which stock a particular store will send, or turn it into the Korean formula. Separate US SPF 50 label.
If the headline says SPF 50 but the photograph says SPF 45, ask the seller for the label on the actual stock. A clear answer is more useful than guessing that one image is simply old.
SPF mainly describes protection against sunburn from UVB. “Broad Spectrum” on a US label includes UVA protection. PA++++ is a UVA grade used on the Korean product; it doesn't establish a US broad-spectrum label or a water-resistance rating. Our Korean sunscreen buying guide explains these labels in more detail.
The American Academy of Dermatology recommends broad-spectrum sunscreen with SPF 30 or higher and water resistance. The US SPF 45 meets the first two stated label criteria, but its directions specifically point you toward a water-resistant product when swimming or sweating. AAD sunscreen selection guidance.
Neither a higher SPF nor a more elegant finish lets you stretch the reapplication interval. For US water-resistant sunscreens, look for an actual 40- or 80-minute statement. We did not verify such a claim for either of the two main versions reviewed here. FDA label guidance.
Older reviews sometimes explain Korean sunscreen by saying US filter options haven't changed. That information can date quickly: the FDA added bemotrizinol as a permitted sunscreen active in June 2026. This does not change the ingredients printed on an existing Round Lab tube. Use the current product label to settle the formula question.
Round Lab describes the US SPF 45 as a lightweight cream with a soft, dewy finish. That's a useful description for narrowing your search if powdery or very matte sunscreens feel unappealing. It is still the brand's description, rather than a wear result from us.
Published experiences also show why a single finish label can be misleading. In his comparison, Spencer Wong found the Korean Birch SPF creamier and heavier than the SKIN1004 and Isntree options he used. Dr Rachel Ho's review described a lightweight, matte finish on her skin, yet found it less moisturizing than its name suggested. These are individual experiences with the Korean product, not a consensus or a comparison with the current US tube.
For the US version, Esquire's SPF 45 review describes a lotion-like feel. That supports investigating it if this is your texture preference. It doesn't prove that it will sit well over your particular moisturizer or foundation.
If your skin tends to feel dry, keep a familiar moisturizer underneath while you assess the sunscreen. If you tend to get shiny, try it over fewer rich leave-on layers before deciding you need to replace several products. Change the layers underneath rather than using less sunscreen to make the finish lighter.
The reviewed SPF 45 is untinted. It isn't intended to even your complexion like a skin tint, and we can't promise an invisible finish on every skin tone. If some coverage is part of the purchase decision, compare Korean tinted sunscreen options with an actual shade match in mind.
The US SPF 45 label contains niacinamide, glycerin, birch juice, allantoin and hyaluronic acid, alongside its UV filters and other formula ingredients. It also lists Anthemis nobilis flower oil and Pinus sylvestris leaf oil. The official Korean ingredient image likewise lists chamomile flower oil and pine leaf oil.
That makes neither formula automatically unsuitable for you. It does mean that “for sensitive skin” or botanical imagery isn't enough information if you already know you react to a particular ingredient. Compare the complete list with products you tolerate, including the oils and extracts that aren't featured on the front.
We wouldn't buy it specifically to treat acne, eczema or redness. The presence of niacinamide or birch juice doesn't establish those outcomes for the finished sunscreen, and we found no basis for promising that you won't develop a reaction or breakout.
The US label says to avoid damaged or broken skin, keep the product out of your eyes and stop use and ask a doctor if a rash occurs. Follow those directions even if the product's marketing sounds reassuring. US warnings and full ingredient list.
Keep the order straightforward: your usual skincare, sunscreen, then makeup if you wear it. Let your moisturizer settle before applying the sunscreen, so you can spread it evenly without chasing slippery layers around your face.
The inspected US directions specify:
These are the SPF 45's label directions, not instructions copied from a Korean sunscreen review. Check the packaging on any other version you buy.
Remember the areas around your hairline, ears and neck, and use shade, clothing and a hat as well. Store the tube away from excessive heat and direct sunlight. Sunscreen shouldn't spend the summer warming on a car dashboard. FDA application and storage advice.
If a reviewer says a light layer kept them comfortable for hours, that is their anecdote. It doesn't replace the amount or reapplication directions on your own tube.
The official US shop listed the SPF 45 at $24.99 for 50 mL when checked on September 8, 2026, before its temporary promotional discount. That is approximately $0.50 per mL, before shipping or tax. Prices and promotions can change. Price and size source.
Use that unit price to compare the same formula across shops. A cheaper Korean SPF 50+ listing is a different product comparison; a 10 mL mini or two-pack also needs its own calculation. We haven't assigned a cost per day because the amount you cover and the number of reapplications vary.
Before ordering, give your intended day as much attention as the price:
The strongest reason to buy Round Lab is a specific formula that suits how you use sunscreen. If the seller can't tell you which one will arrive, leave that cart for a clearer listing.
Compare Korean sunscreens for sensitive skin using exact US formulas, fragrance, known triggers and water resistance, with a careful introduction plan.
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