Round Lab vs. BoJ Sunscreen: Which K-Beauty SPF Is For You?

If you've spent more than five minutes browsing K-beauty skincare forums this year, you've almost certainly seen these two sunscreens mentioned in the same breath. ROUND LAB Birch Juice Moisturizing Sunscreen and Beauty of Joseon Relief Sun: Rice + Probiotics are arguably the two most talked-about Korean sunscreens on the market right now, and for good reason - both deliver SPF50+ PA++++ protection in a lightweight, no-white-cast formula that actually feels good to wear every day. But "both are great" isn't a very useful answer when you're standing in front of your cart trying to pick one. So let's break down exactly how they differ, who each one is actually best for, and which one deserves a spot in your routine.

Why These Two Get Compared So Often

Korean sunscreens built their global reputation on solving the two biggest complaints people have about sun protection: the heavy, greasy feel of traditional SPF, and the dreaded white cast left behind by mineral filters. ROUND LAB and Beauty of Joseon both tackle this with modern chemical (or hybrid) filter systems, plus a "skincare-first" formula built around a single hero ingredient - birch sap for ROUND LAB, fermented rice water and probiotics for Beauty of Joseon. The result in both cases is a sunscreen that doubles as a light moisturizer, which is exactly why they keep showing up in "best Korean sunscreen" roundups side by side.

ROUND LAB Birch Juice Moisturizing Sunscreen: The Hydration Pick

ROUND LAB built its entire brand identity around birch sap (also called birch water or birch juice), an ingredient long used in Korean folk skincare for its soothing, moisture-retentive properties. The sunscreen leans hard into that hydration angle - the texture is closer to a lightweight lotion than a typical sunscreen, and it sinks in with almost no tackiness or pilling under makeup.

What stands out about this formula in particular:

Texture and finish: A semi-matte, slightly dewy finish that suits combination and oily skin without feeling greasy, while still being gentle enough for dry or dehydrated skin that needs the extra moisture boost.

Sensitivity-friendly: Birch sap is known for being calming, which is part of why this sunscreen is frequently recommended for reactive or easily irritated skin - it rarely stings going on, even on skin that's freshly exfoliated or post-procedure.

Layering: Plays nicely under makeup and other skincare without that "rolling" or balling-up effect some sunscreens cause when layered with serums.

If your priority is comfort and hydration above everything else - especially if you deal with dry patches, tightness, or general sensitivity - this is the formula built for you. Right now there's a Triple Set bundle of the ROUND LAB Birch Juice Moisturizing Sunscreen available on OLIVE YOUNG Global, which is worth checking if you go through sunscreen quickly or want to stock up - use code JHBB0302 at checkout for an extra discount on top of the bundle pricing.

Beauty of Joseon Relief Sun: Rice + Probiotics: The Cult Favorite

Beauty of Joseon's Relief Sun has been a runaway bestseller for years, and its formula is built around fermented rice extract and probiotics - ingredients pulled straight from traditional Korean beauty rituals, repackaged into a modern SPF. It's thinner and runnier than most sunscreens, which makes it extremely fast to absorb, but also means you need to be a little more careful about application amount to get full protection.

Key characteristics:

Texture and finish: A dewy, glowy finish that many people use as a makeup primer on its own. It has almost no scent and blends in within seconds.

Brightening feel: The rice and probiotic complex gives skin a slightly brighter, more even-toned look immediately after application, which is part of why it's so popular as a "no-makeup makeup day" base.

Value: It's typically sold at a lower price point per use than many competitors, which is a big part of its cult following - people are willing to repurchase it constantly because it doesn't feel like a splurge.

The tradeoff some users report: because the formula is thin and fast-absorbing, a small number of people with very dry or sensitive skin find it slightly less cushioning than a lotion-style sunscreen like ROUND LAB's, and a few users with deeper skin tones have mentioned a faint, temporary white cast immediately after application that fades as it sets.

Side-by-Side: Which One Fits Your Skin?

Neither of these sunscreens is objectively "better" - they're built for slightly different priorities, and the right pick really comes down to your skin type and what you want from your base routine.

Choose ROUND LAB Birch Juice Sunscreen if: you have dry, sensitive, or easily irritated skin; you want a sunscreen that doubles as a moisturizer so you can simplify your morning routine; you tend to experience tightness or flaking with thinner sunscreen formulas; or you're looking to stock up with a multi-pack since you reapply often.

Choose Beauty of Joseon Relief Sun if: you have normal to oily skin and want the lightest possible texture; you like using your sunscreen as a dewy makeup base; budget-per-use matters to you; or you're a sunscreen beginner who wants a foolproof, low-fuss option that's nearly impossible to overuse.

Plenty of people in the K-beauty community actually keep both in rotation - Beauty of Joseon for everyday wear under makeup, and ROUND LAB for nights, travel days, or whenever skin feels a little more reactive than usual.

A Closer Look at the Hero Ingredients

It's worth slowing down on what actually makes each of these formulas tick, because the "hero ingredient" isn't just marketing - it genuinely shapes how each sunscreen feels and performs.

Birch sap (also labeled birch water or betula platyphylla juice) has been collected and used in parts of Northern and Eastern Europe and Korea for generations, prized for its high mineral and amino acid content. In skincare, it functions primarily as a humectant - pulling and holding moisture in the skin barrier - while also containing small amounts of antioxidants. ROUND LAB uses it as the base of nearly their entire moisturizing line, not just the sunscreen, which is why the brand has built such a consistent identity around "hydration without heaviness."

Fermented rice water, on the other hand, has an even longer history in Korean beauty culture - the often-cited legend of palace ladies washing with leftover rice water to keep skin soft and bright predates modern skincare by centuries. Fermentation breaks the rice down into smaller, more skin-absorbable compounds, and pairing it with probiotics is meant to support the skin's microbiome alongside the brightening effect. Beauty of Joseon leans on this ingredient across its whole catalog, from serums to the Relief Sun itself, which is part of why the brand markets itself so heavily around "traditional Korean beauty, modernized."

Pricing and Value Per Use

Cost is rarely the deciding factor between two good sunscreens, but it does matter if you're someone who reapplies multiple times a day or burns through a tube quickly in summer. Beauty of Joseon's Relief Sun has built much of its cult status on being genuinely affordable for the quality it offers, which makes it easy to repurchase without much thought. ROUND LAB sits a little higher on price per milliliter, but the brand frequently runs bundle deals - like the Triple Set bundle linked above - that bring the effective per-tube cost down close to single-bottle Beauty of Joseon pricing, while giving you a few months' supply at once so you're not reordering constantly.

If you're trying to build a long-term, low-maintenance routine and don't want to think about restocking sunscreen every few weeks, buying a multi-pack of whichever one suits your skin is usually the more practical move than buying single bottles repeatedly.

How They Hold Up Through a Full Day

One thing reviewers consistently bring up is how each sunscreen behaves hours after application, not just in the first ten minutes. ROUND LAB's slightly richer texture tends to hold its hydrating feel longer on dry skin, meaning less of that "tight" sensation by mid-afternoon that thinner sunscreens can sometimes cause on dehydrated skin types. Beauty of Joseon's thinner formula absorbs faster up front, but oily-to-combination skin types often report it controls shine reasonably well through a full workday, especially when set with a light powder.

Neither formula is marketed as fully waterproof or sweat-proof, so if you're spending the day outdoors, swimming, or doing intense exercise, reapplication (or a sunscreen specifically labeled for water resistance) matters more than which of these two you started the day with.

Frequently Asked Questions

Do either of these leave a white cast on deeper skin tones? Both are formulated primarily with chemical/hybrid filters rather than heavy mineral filters like zinc oxide, so white cast is minimal for most users. Beauty of Joseon has occasionally been reported to leave a very faint, temporary cast on some deeper skin tones immediately after application, which typically settles within a minute or two.

Can I use these under makeup? Yes - both are designed to be makeup-friendly. ROUND LAB's slightly thicker texture gives makeup a bit more grip, while Beauty of Joseon's thinner, dewier finish works well as a glow-boosting primer.

Are they reef-safe? Always check the current ingredient list on the product packaging before travel, as formulations can be updated by the brand over time; this is true for any sunscreen, not just these two.

Which one lasts longer per bottle? Because Beauty of Joseon's formula is thinner, a little goes further per use for some people, though this varies depending on how generously you apply.

The Bottom Line

If you want this decision boiled down to one sentence: pick ROUND LAB Birch Juice Moisturizing Sunscreen for comfort, hydration, and sensitive skin, and pick Beauty of Joseon Relief Sun for the lightest possible texture and best value-per-use. Both are well-formulated, SPF50+ PA++++ sunscreens that have earned their reputations for good reason, so you genuinely can't go wrong picking based on your skin's needs rather than hype alone.

If the hydration-focused formula sounds like the better fit for your skin, the ROUND LAB Birch Juice Moisturizing Sunscreen Triple Set is currently available on OLIVE YOUNG Global - code JHBB0302 applies at checkout. For more K-Beauty guides, browse the SeoulLocalPulse K-Beauty section.