Syncly Social Index
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Hair
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K18 vs Kérastase on video, September 2026
Kérastase edged K18 on the Syncly Social Index in September, 65.6 to 61.9, on more videos (919 vs 757). 70 videos named both. In the 40 we read, 15 praised both and 2 leaned each way.
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Side by side
Kérastase ranked 2nd in hair and K18 3rd. Kérastase led on share of voice (77.8 vs 55.6), momentum (44.4 vs 33.3; share up 16.2% from August vs 10.8%) and high reach (77.8 vs 44.4; 4.9% vs 3.7% of videos over 100K views). K18 led on sentiment (50 vs 0; 37.1% vs 29.5% organic positive) and creator breadth (88.9 vs 77.8). Both scored 100 on untagged reach. The Syncly Social Index measures attention and reaction in social video and does not test how well a product works.
Syncly Social Index metrics, September 2026. The higher value in each row is bold.
| K18 | Kérastase | |
|---|---|---|
| SSI score | 61.9 | 65.6 |
| Videos (month) | 757 | 919 |
| Change in share vs. last month | +11% | +16% |
| Untagged mentions | 21% | 35% |
| Positive (organic videos) | 37% | 30% |
| Videos with 100k+ views | 3.7% | 4.9% |
| Creator breadth | 95% | 95% |
When creators compare them
15 of 40 praised both, usually as different steps. grubmode calls the K18 mask "expensive but worth it" and keeps Kérastase in her serum rotation, grwmia.o builds a routine around Kérastase Gloss and adds the K18 mask, and isabellakatee uses K18 for damage and Kérastase Genesis for thinning. Two leaned K18: sofiahairhealth rated K18 9/10 vs Kérastase Glaze Drops 8/10, and nipunkapur won't rebuy a Kérastase glaze milk. Two leaned Kérastase: one Arabic-language creator said K18 is great but overpriced, and Aleja Franco called the K18 detox shampoo not worth 45 euros while praising Kérastase oils.
Which one creators prefer in videos that mention both
Videos that compare them
Which one to choose
Choose K18 if you want what these creators use it for: a repair mask for damaged or bleached hair (howrosdoesit, vivianyunn) or the Air Wash dry shampoo (alexisdimaya, lyssokada). Choose Kérastase if you want an oil or serum for gloss and frizz (Alex Gaboury, vivianyunn) or Genesis for thinning (isabellakatee). Price is the most common K18 complaint in the sample (overpriced, pricey).
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Frequently asked questions
Benchmark your brand against competitors
The Syncly Social Index scores brands from 0 to 100 using short-form video on TikTok, Instagram Reels and YouTube Shorts. It combines six signals: video share of voice (25%), untagged mentions (20%), momentum (15%), sentiment (15%), high-reach videos (15%) and creator breadth (10%). Each signal is scored relative to the other brands in the same category for the month. Sentiment and untagged figures come from a sample of videos; any claim about a specific video links to that video.