How to Read Chess Analysis
The Eval Number Tells You Who Is Ahead, Measured in Fractions of a Pawn
Reading chess analysis comes down to three things. You need to read the eval. Eval is short for evaluation. Eval is the engine's score for the position on the board right now. An engine is a chess program that calculates the best moves. Stockfish is the most widely used free chess engine. It plays out millions of positions in seconds and scores each one. You also need to read the depth. And you need to read the move symbols. Once you know those three, any analysis screen makes sense.
The eval number is measured in pawns, or in centipawns. A centipawn is one hundredth of a pawn. So an eval of +1.00 means White is ahead by about one pawn's worth of advantage. An eval of -0.50 means Black is ahead by half a pawn's worth.
The sign tells you who is ahead. A plus number favors White. A minus number favors Black. Zero means the position is roughly equal.
Sometimes the eval will not show a number at all. Instead you will see something like M3, or #3. M3 means mate in 3. That means one side has a forced checkmate in three moves. No matter what the other side tries, the checkmate happens. When you see an M or a # next to a small number, stop looking at the pawn count. Someone is about to get checkmated.
Depth Tells You How Far Ahead the Engine Looked, and Whether to Trust the Number
Depth is the second thing you need to read. Depth tells you how many half-moves the engine looked ahead before it gave its eval. Chess players call a half-move a ply. One ply is one side's move. If White moves and then Black moves, that is two plies.
A low depth means the engine only checked a few moves ahead. It gave you a quick guess. A high depth means it checked much further. That guess is far more solid.
This matters because a fast eval can be wrong. Say the engine shows +0.30 at depth 12. That looks close to equal. Let it run to depth 24, and the same position might jump to +2.50. Maybe there was a knight fork three moves down that the shallow search missed. A fork is a move where one piece attacks two enemy pieces at once, so the opponent can only save one.
So when you check an eval on your phone between moves, treat it as a rough guess. When you want the real answer, in a critical moment like a queen trade or an endgame, let the engine run longer. Depth is what separates a hint from a verdict.
The Symbols Grade One Move, but No Two Sites Grade Blunders the Same Way
The third thing to read is the move symbols. Chess uses a set of symbols next to a move to grade it. Two exclamation marks (!!) mean a brilliant move. One exclamation mark (!) means a good move. An exclamation mark with a question mark (!?) means an interesting try. A question mark with an exclamation mark (?!) means a dubious move, also called an inaccuracy. One question mark (?) means a mistake. Two question marks (??) mean a blunder, a bad mistake that loses material or the game.
Analysis sites turn these symbols into color-coded labels like inaccuracy, mistake, and blunder. Chess engine analysis grades each move you make on a wider scale, too, one that can run all the way from Brilliant down to Blunder. Here is the part that trips people up. Those labels are not set by one fixed centipawn number. Lichess, a free chess site, grades a move by how far it drops your chance of winning. On Lichess, a drop of about 10 out of 100 in win chance counts as an inaccuracy. About 20 counts as a mistake. About 30 or more counts as a blunder. Chess.com uses its own cutoffs, and it does not publish them. So a move Lichess calls a mistake might get graded differently on another site. There is no single centipawn number that means blunder everywhere.
A full game report goes further than single-move symbols. It adds up every move's centipawn loss into one accuracy percentage for each player. Centipawn loss is the drop in position value compared to the engine's best move for that spot. Many reports also draw an evaluation graph, a line that plots the position's value across the whole game, so you can see exactly where it swung. Some reports name the opening you played and mark the exact move where you left known theory.
Reading One Game's Symbols Tells You What Happened, Not What You Keep Doing Wrong
Here is the catch. Every symbol and label you just learned is scored inside one game. A ?? next to move 24 tells you that move was a blunder, in that game, on that day. It does not tell you if you make the same kind of blunder over and over, across many games.
That gap matters more than any single symbol. Say you play 20 games this month. In five of them, you lose a piece to a fork. A fork is one move that attacks two of your pieces at the same time, so you can only save one. Each of those five games shows its own ?? on its own move. Nothing on the analysis screen adds them up and says "you keep falling for forks." You would have to notice that yourself, game by game.
The same goes for a pin. A pin is when one of your pieces cannot move without exposing a more valuable piece behind it to attack. Or a hanging piece. A hanging piece is a piece left where the opponent can simply capture it for free. Or missing a rook on the 7th rank, a rook placed on the row just in front of the opponent's pawns, where it attacks many pawns at once. Each one shows up as an isolated blunder symbol in a single game. None of them get grouped into a pattern by the symbols alone.
That is the real limit of reading one game's analysis. It tells you what happened. It does not tell you what you keep doing. Finding the mistake type you repeat, across ten or a hundred games, is a different job than reading move symbols. That job is what BlackBox Chess is built to do.
BlackBox Checks Your Last 10 Games for Free and Names Your #1 Recurring Mistake
You do not have to find your repeated mistake by hand, game by game. BlackBox Chess is a tool built to do that step for you. You connect your Chess.com or Lichess account, or upload a PGN file. PGN stands for Portable Game Notation. A PGN file is the standard text file chess sites use to save a game's full move list.
From there, Stockfish runs across your last 10 games. The check takes about 60 seconds. You do not need an account. You do not need a card. At the end, it names your number one recurring mistake, the pattern showing up most across those games, not just in one of them.
If you want the fuller picture, the paid Full Report costs $10, a one-time charge. It covers 100 games instead of 10. It ranks every recurring mistake pattern you have, by severity on a 1-to-8 scale and by how often it happens. It includes real examples pulled from your own games, and a fix course built around your specific patterns. You can see what a finished report looks like in this real example report: https://blackboxchess.app/report/3f128113-1baa-4d77-ad1e-ccbada689fa0
Reading the eval, the depth, and the symbols on one game will always tell you what happened in that game. It will not tell you what you keep doing. That is the gap BlackBox exists to close. Try the free check at https://blackboxchess.app/.