How does chess.com calculate accuracy?

It is also my current belief that a "perfect" chess game would also end in a draw (due to not being able to force a win, even with slight advantage, due to the Principle of Two Weaknesses). However, the "perfect" chess game resulting in a draw has not been proven; you shouldn't declare "always ends in a draw" as if this is a proven fact. As incredible as current chess computers are, they are far from solving chess.

I am noticing that less failures at the end of a game results in a higher accuracy! Unknown last 10 moves 30% , but that seems to be the problem stems. I have played games with 1 inaccuracy and 87% accuracy. I have played a game with 3 inaccuracy and receive 92%. Go figure? The difference was where was the inaccuracies, beginning of the game or towards the end.

Extremely badly.

We know that a game of chess where both sides play the best moves results in a draw. Knowing it is not the same as being able to prove it deductively, which is and always will be completely impossible. It's an inferential proof. That's the same kind of proof that leads us to understand gravity.

Then you don't KNOW it.

I also believe chess is probably a draw with best play, but this isn't proof. It is our educated guess. Perhaps educated guesses are still correct more often than not, yet they are still guesses.

Maybe one day a computer or mathematician will creatively invent some amazing way to illustrate chess is a draw with best play, but I don't see this happening anytime soon (if ever).

I know it as completely as I know gravity exists though. That seems fairly certain!

If a deductive proof cannot exist, then we go to the next best thing, which is an inferential proof.

Unless you can prove I'm wrong, it's looking like I'm right!

Yes, but then we don't claim "know." Informally, I understand what you mean and I agree. I just get very picky with technicalities and definitions because I am using "know" as as absolute and a synonym for "certainty."

If we use "know" as "more likely correct than not", then okay fine. I might even say "beyond a reasonable doubt" could count as "know" if I can generous with the definition, but even still I believe there is reasonable doubt about chess being a draw with best play. I suspect it is a draw, but I also wouldn't be shocked if white has a forced win with best play.

We don't really need to keep this overused topic going though. I'm sure you and I have both encountered this in many forum threads over the years.

I think knowledge is very highly confirmed and justified belief. Confirmed is regarding empirical demonstration which has never been seen to be false in hundreds of millions of games and justified means that it's in accordance with theory which says that chess ought to be drawn with best play.

That's good enough for me. All proofs rest on axioms which come from the same place, really.

Fair enough.

Absolute knowledge doesn't make sense. It's equivalent to "Large Sky Fairy exists".

To our great friend Optimissed you are right! But I see a perfect game is not a game where computers play in each move leads to a draw. That's not perfect that's boring. Magnus Carlson and whoever he plays and they come into a draw that's perfect. Perfect because there's excitement this interest there's hope desire to see a winner. The interest to see someone play great moves. That is what chess is and has been about. I know that there are many who would like to see " the perfect game " an (mathematical or scientific draw) but after watching a few of them I'm sure they would rather see a game between Magnus Carlson and someone that's a perfect game.

"After completing this game and running the analysis, the report said I made 3 inaccurate moves, on moves 3, 7 and 8. In my mind, that means my accuracy was about 8/11 or 72%, but the report said I had 94.5% accuracy. How does chess.com calculate accuracy?"

With a ouija board.

The way chess.com calculates accuracy is quite stupid, since there is no clear formula. I recommend chess.com to use this formula. One great, brilliant, best move or book move is worth 1 point, excellent move 2/3 pts, good move 1/3 pts, inaccuracy or mistake or missed_win or blunder is 0 pts. Then add all the points together and divided it by the total amount of moves. So, the formula should be “total_points / total_moves”.

100⋅e^−0.000025⋅∣cp best move​−cp your move​∣^2that's how you can calculate the accuracy of each move.
to make it for a entire game you need to do the arithmetic mean including all the moves.
the maybe do not use 100 but something like 102 or 103 in the opening or to book moves to increase the opening accuracy to almost 100% when you follow the book.

good grief, ms. bear.

https://support.chess.com/en/articles/8572705-how-are-moves-classified-what-is-a-blunder-or-brilliant-etc#h_cbb78e210b

What happened to stockfish

"After reviewing the game under the CAPS microscope, the system then applies a value (a grade, just like taking a test in school). There are several factors considered:

• how many top moves (moves that matched the engine's top choice or were equal in score to that choice)
• how many inaccuracies (a move that changes the position's evaluation slightly in the negative direction)
• how many blunders (a move that changes the position's evaluation greatly in the negative direction)
• patterns of strength (our own algorithm that determines the sequencing of these scores per game timeline)

By reviewing these factors and several others, a player receives a score, expressed as a percentage, 0 to 100. A CAPS of zero percent means a game played with one of the worst moves on every turn, and 100 percent is a game where only the top choice of the world's strongest chess computers was played on every move.  "

https://www.chess.com/article/view/better-than-ratings-chess-com-s-new-caps-system