Serums & ampoules
Actives, layering order, and what actually absorbs versus what just sits on top under moisturizer.
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222 serums & ampoules compared, lowest price-per-mL first
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More about serums & ampoules
Serum claims are easy to make and hard to verify from an ingredient list alone. We focus on what's actually checkable: the key active ingredient, how it's positioned to be used, and whether the price reflects real concentration or just clever bottle design.
Across the serums & ampoules in our catalog, the median price per mL is $0.516 (based on 215 priced products), per our November 2026 K-Beauty Price Report.
Actives like these work best on a clean base, so see our cleanser comparisons for what pairs well in a double-cleanse routine before layering a serum on top.
Read more about how we compare serums & ampoules
Serum claims are easy to make and hard to verify from an ingredient list alone. We focus on what's actually checkable: the key active ingredient, how it's positioned to be used, and whether the price reflects real concentration or just clever bottle design.
Layering order matters more with serums than almost any other category, since applying a heavier serum before a lighter one can block absorption entirely. Most Korean routines apply thinnest-to-thickest, with treatment serums (vitamin C, retinoids, exfoliating acids) generally going on clean skin before hydrating or barrier-focused ones.
Serum pricing varies enormously by size and concentration claim, which makes price-per-mL a genuinely useful cut-through here. We calculate it for every product in the catalog, so a 30mL serum at $18 and a 50mL serum at $24 can be compared on equal footing rather than sticker price alone.
How we research serums & ampoules
- - We identify the key active ingredient and how it's marketed to be used
- - We note layering order and what it's meant to pair with
- - We calculate real price-per-mL, not sticker price
- - We label evidence status and surface Olive Young Award data where it exists
Guides & comparisons
- Best Calming Korean Skincare for Redness
A four-step routine built around centella, heartleaf, and madecassoside, each pick genuinely positioned for redness-prone or reactive skin.
- Best Korean Serums for Sensitive Skin
Three fragrance-free, centella-or-minimal-formula serums, from a single-ingredient option to a genuinely renewed calming formula.
- Most Hydrating Korean Serums
Four hyaluronic-acid-forward serums ranked by price, from real barrier lipids to an 8-type hyaluronic acid blend with a genuine Olive Young placement.
- Best PDRN Serums in K-Beauty
Three serums where PDRN is genuinely the headline active, not a minor supporting ingredient, ranked by price. Includes a real disclosure on one entry.
- Best Korean Vitamin C Serums
Four verified vitamin C serums ranked by price, spanning every real form: pure ascorbic acid at two strengths, a stabilized derivative, and a natural plant extract.
- Best Korean Serums for Dark Spots
Four serums ranked by price, from a natural extract-based option to maximum-strength pure ascorbic acid, each genuinely targeted at pigmentation.
- Best Fragrance-Free Korean Serums
Sixteen serums in our catalog are confirmed fragrance-free with verified retailer pricing. Here are eight genuine standouts across price tiers and purposes.
- Dr. Althea vs. Klairs Vitamin C Serum: Which Is Gentler?
Dr. Althea's stabilized derivative is fragrance-free; Klairs uses pure 5% ascorbic acid, costs less, and contains fragrance. See the side-by-side.
- COSRX Snail 96 vs. Wellage Hyaluronic Ampoule
Nearly the same price, both fragrance-free, but a concentrated 96% snail-mucin essence against an eight-weight hyaluronic acid blend with supporting PDRN.
- SKIN1004 Probio-Cica vs. numbuzin No.5+
A fermented-centella, ceramide-boosted barrier formula against an eight-active glutathione-and-TXA brightening blend, two genuinely different jobs.
- AESTURA Hydro Essence vs. Round Lab Birch Serum
Structural barrier-lipid hydration at the site's lowest per-mL price against a broader birch-and-vitamin-C formula addressing hydration, brightening, and soothing together.
- Wellage vs. Round Lab Birch Serum
An eight-weight hyaluronic acid blend with a real Olive Young placement against a more botanically-diverse birch-and-vitamin-C formula, at a real price gap.
- Purito vs. Round Lab Birch Serum for Redness
Identical price, both fragrance-free, but Purito is specifically built for reactive skin with real ceramide backing, while Round Lab takes a broader, general-hydration approach.
- Purito vs. SKIN1004 Probio-Cica
Two ceramide-boosted, niacinamide-and-madecassoside centella formulas at nearly the same price, split by a disclosed-concentration peptide approach versus a fermentation angle.
- Torriden DIVE-IN vs. Round Lab Birch Serum
Nearly identical price, both fragrance-free, but a single-purpose five-weight hyaluronic acid serum against a broader formula covering hydration, brightening, and soothing together.
- SKIN1004 Centella vs. SKIN1004 Probio-Cica
The brand's own site is direct about this one: not a simple swap. A single-ingredient centella ampoule against a fermented, ceramide-boosted intensive formula.
- Klairs Vitamin Drop vs. Anua Niacinamide+TXA
A gentle, beginner-positioned 5% vitamin C serum against a clinically-dosed 10% niacinamide and tranexamic acid pairing built for stubborn pigmentation specifically.
- VT Reedle Shot 100 vs. medicube PDRN Serum
A spicule delivery system with low-concentration PDRN, fragrance-free, against a genuine PDRN-and-peptide firming formula that contains fragrance.
- numbuzin No.5+ vs. Goodal Dark Spot Serum
A clinically-concentrated 8-active brightening formula against a simpler, natural green-tangerine approach, both targeting dark spots, at nearly identical price.
- Klairs Vitamin Drop vs. Goodal Green Tangerine
Two beginner-friendly vitamin C serums at nearly identical price, both containing fragrance, split by ingredient source: pure low-percent ascorbic acid vs. natural tangerine extract.
- COSRX Vitamin C 23 vs. numbuzin No.5+
Maximum-strength 23% pure ascorbic acid against an eight-active, glutathione-forward clinical blend with no pure ascorbic acid at all.
- VT Reedle Shot 100 vs. Anua PDRN Serum
PDRN as a low-concentration supporting ingredient behind a spicule delivery system, against PDRN as the genuine headline active, at a real 53% price gap.
- Torriden DIVE-IN vs. Wellage: Which Hyaluronic Serum Wins?
Wellage packs more HA weights, added PDRN, and a real Olive Young #3 win, all at a lower price than Torriden's simpler formula. See the side-by-side.
- Torriden DIVE-IN vs. Purito Centella Serum
Nearly identical price, both fragrance-free, but a pure hydration-focused hyaluronic acid formula against a calming-and-barrier centella-ceramide-peptide blend.
- Goodal vs. Anua Niacinamide+TXA for Dark Spots
A natural green-tangerine vitamin C approach against a clinical-concentration niacinamide-and-tranexamic-acid pairing, with a real fragrance-status difference between them.
- BoJ Glow Serum vs. COSRX Snail 96
A gentle, layer-with-anything niacinamide-and-propolis default against a concentrated 96% snail mucin essence, for two genuinely different jobs in a routine.
- medicube PDRN vs. BoJ Glow Serum
A peptide-and-PDRN firming treatment against a gentle everyday niacinamide default, different price tiers and different fragrance status entirely.
- AESTURA Hydro Essence vs. SKIN1004 Centella
Real barrier-repair lipids against a single-ingredient calming extract, both fragrance-free, both among the cheapest serums on the site.
- COSRX Snail 96 vs. BoJ Revive Serum
A concentrated 96% single-focus snail mucin essence against a broader six-ingredient ginseng-and-snail formula, at more than double the price per mL.
- SKIN1004 vs. Purito Centella Serum
A single-ingredient centella ampoule at the lowest price on the site against a renewed multi-active formula with a real disclosed concentration and added ceramide.
- Torriden DIVE-IN vs. AESTURA Hydro Essence
A five-molecular-weight hyaluronic acid serum against a squalane-and-cholesterol barrier essence, at nearly identical price, for two different hydration strategies.
- Dr. Althea vs. Goodal Green Tangerine
Two gentler vitamin C entry points that avoid pure ascorbic acid entirely, one via a stabilized derivative, the other via green tangerine extract, with a real price gap.
- Anua Niacinamide+TXA vs. BoJ Glow Serum
A targeted 10% niacinamide and tranexamic acid pairing for stubborn pigmentation against a gentle 2% niacinamide-and-propolis all-purpose cult favorite.
- Anua PDRN vs. medicube PDRN Serum
Two PDRN serums in identically-sized bottles, one leaning multi-active regenerative, the other peptide-emphasized firming, with a real 21% price gap between them.
- COSRX Vitamin C 23 vs. Goodal Green Tangerine
Pure 23% L-ascorbic acid at a premium per-mL price against a green-tangerine-derived vitamin C with a genuine, repeated Olive Young bestseller record.
- Best Korean Serums: 8 Picks by Skin Concern
Brightening, hydration, anti-aging, and the signature K-beauty snail mucin category, matched to the concern that actually determines which one is right for you.
- COSRX Vitamin C 23 Serum vs. Dr. Althea Gentle Vitamin C Serum
One is 23% pure ascorbic acid built for visible results fast. The other is a stabilized, beginner-friendly form built not to sting or oxidize. Here's which one actually fits your skin.
- How to Choose a Korean Serum: A Practical Guide
Layering order, what active-ingredient percentages actually mean, and the outdated "never mix vitamin C and niacinamide" rule that still shows up everywhere.
- Best Value Korean Skincare: The Real Cost-per-mL Leaders, Category by Category
Sticker price and true value aren't the same thing. Here's the actual lowest cost-per-mL pick in each category, verified against real, currently tracked retailer pricing, not just the cheapest-looking bottle.
Frequently asked
What order should I layer serums in?
The general rule is thinnest-to-thickest texture. Treatment serums (vitamin C, exfoliating acids, retinoids) typically go on clean skin first, followed by hydrating or barrier-focused serums, then moisturizer to seal everything in.
Does a higher active-ingredient concentration always mean better results?
No. Higher concentrations can mean faster or more visible results, but also higher irritation risk, especially for actives like vitamin C or retinol. A lower concentration formulated well and used consistently often outperforms a high concentration that's too harsh to use regularly.
How is price-per-mL calculated?
We divide the listed price by the product's size in milliliters. It's a rough way to compare what you're actually paying, since bottle sizes vary a lot within a category and sticker price alone can be misleading.
What's the difference between "Research-based" and "Hands-on tested"?
Research-based means our assessment comes from pricing, ingredients, and published information, not personal use. Hands-on tested means someone on our team actually used the product. We label every product one or the other so it's never ambiguous which kind of evidence you're looking at.