About the club

Every mainstream chess resource teaches openings the way grandmasters play them. The Opening Club answers a different question: what actually wins for players rated 400 to 1800. Everything on this site is computed from the Lichess open database, a public archive of billions of rated amateur games released under a CC0 license.

The rating bands

Statistics are reported at four bands: 600 (games under 1000), 1000 (1000 to 1400), 1400 (1400 to 1600), and 1800 (1600 to 2000), pooling rapid and blitz. A game counts toward a band when the average of the two players ratings falls inside it and the gap between them is at most 300 points. Every statistic on the site is labeled with its band and its sample size.

Win rates and popularity

Win, draw, and loss rates per opening per band come from the Lichess opening explorer, keyed by position so transpositions count. Popularity is the share of all games in a band that reach the opening position.

The Blunder Rate

Each month the club replays rated rapid and blitz games from the Lichess database dumps. A game counts as an early blunder for an opening when, within the first 24 half-moves and after the game leaves known theory, the material balance swings three or more points against the side that opening belongs to. The trap hit rate measures how often games pass through a known trap line. Both numbers are recomputed from scratch every month and versioned, so the methodology behind any published figure is pinned.

Two limits worth stating plainly. The blunder rate is a material-swing proxy, not an engine evaluation, so it catches lost pieces and missed tactics but not quiet positional mistakes. And because it is computed from a game sample rather than the full explorer corpus, its sample sizes are far smaller than the win-rate samples; that is why every blunder figure on the site carries its own n.

Tier grades

Grades from S to D combine four inputs per band and color: score for the opening color (with a statistical penalty for small samples), popularity, blunder resistance, and sample size floors. The exact formula ships in the site source, and every stored grade keeps its full set of intermediate values, so any grade can be recomputed and audited. An opening can be S tier at 800 and C tier at 1600; that is the point of the site.

Honest numbers

Where a sample is too small to grade, the site says so instead of showing a number without context. Bands with no data yet render as exactly that.

Questions or corrections: contact the club. Some links on the site are affiliate links; see the disclosure.

Statistics computed from the Lichess open database.