Methodology
How CS2 Market Indexes Work
A CSSkinLab market index is a single number representing the total median market value of every priceable CS2 variant inside a defined slice — a category like Knives or Stickers, a single collection like The Mirage Collection, or the entire catalog (ALL_ITEMS). Once per day at 06:00 UTC the worker takes the latest cross-market median price for every SKU with at least one marketplace reporting in the last 24 hours, sums those medians in cents, and writes a snapshot. The chart you see on each page is the historical sequence of those daily snapshots.
Why the median, and why cross-market?
Single-marketplace prices swing on small volume, and arithmetic averages get pulled around by outliers — one mispriced listing on a low-volume skin shifts the mean. The median is robust against those distortions, and pulling it from multiple marketplaces (Steam Market, Buff163, CSFloat, Skinport, DMarket) cancels out platform-specific noise. The result is a stable, comparable number across days.
What gets excluded
Souvenirs are excluded from every index — they live in a separate, low-liquidity sub-market that would distort the signal. The Cases index is weapon-cases-only: sticker capsules, autograph capsules, music-kit boxes, Armory containers and souvenir packages are intentionally out. SKUs whose median hasn't refreshed in the last 24 hours are dropped from the day's total so stale prices don't move the chart.
Day, week, and month deltas
Each delta compares today's snapshot to the snapshot from N days ago — 1 for the D delta,
7 for W, 30 for M — as (today − thenAgo) / thenAgo. If the
historical snapshot doesn't exist (a brand-new collection, for example), the delta renders
as — rather than a misleading zero.