−23%
K18 Leave-In Molecular Repair Hair Mask dupes
K18Leave-In Molecular Repair Hair Mask$75
Lowest price per oz
COSRXPeptide 132 Ultra Perfect Hair Bonding Treatment$13.32 $23
| Fact | K18 | COSRX |
|---|---|---|
| Type | ✓ Bond-repair treatment, both | |
| Key ingredients | sh-Oligopeptide-78 (K18Peptide™) | Tripeptide-132 HCl, Biotin, Soluble collagen, Hydrolyzed hyaluronic acid |
| Size | 50 ml | 120 ml |
| Per ounce | $44.36 / fl oz | $3.28 / fl oz |
| Amazon rank | #1 in Hair Treatment Masks | #15 in Deep Hair Conditioners |
| Sold by | K18 Hair | COSRX |
What matches
Both rebuild broken keratin bonds with a low-molecular-weight peptide (K18Peptide in one, Tripeptide-132 in the other), and both are aimed at bleach, color and heat damage.
The trade-off
This one is rinsed out after a few minutes instead of left in, and it is silicone-and-oil heavy, so fine hair can be left with a slight film K18 never leaves.
Leave-in treatment used on damp hair after shampooing, with no rinse and no conditioner for the first few uses. Works in about 4 minutes.
One more Leave-In Hair Mask dupe
Coco & Eve Hair Repairing Leave-In Treatment
$34−55% per oz
The same repair peptide: sh-oligopeptide-78, which K18 sells as K18Peptide, is fourth on Coco & Eve's list, and both carry hydrolyzed wheat protein and wheat starch in a cetearyl alcohol and behentrimonium chloride leave-in worked through damp hair and left four to five minutes before styling.
What it does worse: K18 is a lighter fluid with denatured alcohol and dicaprylyl ether, while Coco & Eve adds glycerin, arginine, itaconic acid, panthenol, flax and chia extracts and hyaluronic acid.
Leave-In Hair Mask dupes on Reddit
Reddit names L'Oréal's Elvive Bond Repair most, in 9 of the last 100 comments; of the two we pair, Coco & Eve's leave-in comes up in 3 and COSRX's Peptide 132 not at all.
- L'Oréal Elvive Bond Repair9 of 100
- Coco & Eve Hair Repairing Leave-In · one of our picks3 of 100
Sold as Leave-In Hair Mask dupes, and left out
- Kristin Ess+ Peptide Bond Repair Leave-In Treatment. Amazon.com sells it, but the listing calls it 5 oz while pricing it per single ounce, and its ingredient list (C11-15 pareth-12, chamomile, mango butter) is not the one on Kristin Ess's own page (cetearyl alcohol, oat peptide, itaconic acid). We couldn't tell which formula ships.
Compared withK18 Leave-In Hair Mask vs OLAPLEX No.3
Questions
What is the best dupe for K18 Leave-In Molecular Repair Hair Mask?
COSRX Peptide 132 Ultra Perfect Hair Bonding Treatment, at about $13.32, of the 2 dupes compared on this page.
How much cheaper is COSRX Peptide 132 Ultra Perfect Hair Bonding Treatment than Leave-In Molecular Repair Hair Mask?
Roughly 93% less per ounce: $3.28 / fl oz against $44.36 / fl oz.
Is K18 Leave-In Hair Mask worth it?
Leave-In Molecular Repair Hair Mask costs about $75 for 50 ml, about 13.5 times as much per ounce as COSRX Peptide 132 Ultra Perfect Hair Bonding Treatment. If what COSRX does worse, set out in the comparison on this page, doesn't matter to you, the original isn't worth the extra $69.
Which Leave-In Hair Mask dupe does Reddit recommend?
Counted in the 100 most recent Reddit comments that mention K18 with "dupe": L'Oréal Elvive Bond Repair, 9; Coco & Eve Hair Repairing Leave-In, 3.
Is Kristin Ess+ Peptide Bond Repair Leave-In Treatment a dupe for K18 Leave-In Hair Mask?
Not by our rules. Amazon.com sells it, but the listing calls it 5 oz while pricing it per single ounce, and its ingredient list (C11-15 pareth-12, chamomile, mango butter) is not the one on Kristin Ess's own page (cetearyl alcohol, oat peptide, itaconic acid). We couldn't tell which formula ships. Checked 5 October 2026.
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