When Does an Opening Score Mean Something?
Every games-analysis page — including the Chess.com and Lichess tabs here — will show you that you score 75% with one opening and 40% with another. The natural conclusion is to play more of the first. Usually the honest answer is that you cannot tell yet, and this guide shows why, and how many games it takes before you can.
Eight games prove very little
Suppose you have won 6 of 8 games with an opening. A 95% confidence range for your true score with it runs from 41% to 93%. That range includes scores below 50%: on this evidence the opening could be a losing one for you, and the 6 wins mostly luck.
The same 75% score becomes more believable only as the games pile up:
| Games at a 75% score | 95% range for the true score |
|---|---|
| 8 | 41% – 93% |
| 20 | 53% – 89% |
| 50 | 62% – 85% |
| 100 | 66% – 82% |
| 400 | 71% – 79% |
These ranges are Wilson score intervals, a standard method that behaves well with small samples. Draws count as half a point; treating them that way makes the ranges slightly wider than strictly necessary, so they err toward caution.
How many games a real edge takes
The smaller the edge, the more games you need before the range clears 50%:
| Steady score | Games before it is clearly above 50% |
|---|---|
| 55% | 385 |
| 60% | 97 |
| 65% | 43 |
| 70% | 25 |
| 75% | 16 |
Who you played matters as much as how you did
A 50% score against stronger opponents is a better result than 60% against weaker ones. The usual rating curve gives the score you would be expected to make:
| Opponent | Expected score |
|---|---|
| 300 points weaker | 85% |
| 150 points weaker | 70% |
| Same rating | 50% |
| 150 points stronger | 30% |
| 300 points stronger | 15% |
That is why the analysis tabs group results into 7 bands by opponent strength and show your expected score beside the actual one. If an opening's games were mostly against weaker players, its high score may say more about the pairings than the opening.
Reading the tabs well
- Look at the range, not the percentage. The tabs mark a score as a clear edge only when its whole range sits above or below 50%.
- Keep time controls apart. An opening that works in blitz, where surprise matters, may not in slow games.
- Colour changes everything. White scores more in general, so compare each opening with your own overall score for that colour.
- Prefer more months of games. A longer period means more games behind every number.
Try it on any public account on the Chess.com or Lichess tab. No login is needed — your browser asks each site's public data service for the username you type.