What is a brilliant move in chess?
A brilliant move gives up material the opponent can take and remains correct after the capture.
Updated
The four conditions
Every review tool draws the line somewhere different, and most do not say where. These are the exact conditions this one checks before it calls a move brilliant. All four must hold.
- You had a real choice. More than one legal move. A sole check escape is not brilliance.
- Real material is still gone afterwards. At least 1.5 pawns' worth, counted after the engine's best continuation settles. That last clause is what separates a sacrifice from an ordinary trade: if the piece comes straight back, nothing was given up.
- The sacrifice is sound. The move costs no more than 2 points of winning chances against the engine's own choice, and leaves you at 45% or better. A losing sacrifice is a blunder that looked exciting.
- You were not already winning easily. Not already three pawns up. Material handed back from a won position is slop, not brilliance.
Why the test measures material, not evaluation
The obvious way to write that last guard is to check winning chances instead: don't award brilliance to someone who was already at 95%. It sounds right and it destroys the feature.
A mating combination already scores 100% before the first move of it is played. That is what a forced mate means. So a winning-chance guard throws out every sacrifice that leads to mate, which is most of the famous ones. Measuring material instead keeps them: in Morphy's Opera Game, both 13.Rxd7 and 16.Qb8+ classify correctly under the material test and are discarded under the evaluation one.
Why brilliant moves are rarer than you expect
Most games contain none, and that is the correct answer rather than a failure of the detector. The conditions above require a position where giving up material is both possible and objectively best, which is not most positions. If a tool hands out brilliance every few games, it is labelling good moves, not sacrifices.
A move that is the sole line that works gets its own label here, only move, when every alternative is at least 12 points of winning chances worse. Finding the only move is a real skill and worth marking, but it is a different one.
Check your own games
Load a game and every move is labelled against published thresholds, including any sacrifice that met all four conditions above. It is free, there is no account, and there is no cap on how many games you run.
Type rv in front of a Chess.com address to open the review directly, or paste a PGN or Lichess link instead.