Chess Tools
Tools for US Chess (USCF) players — compare two players head-to-head across every rating system, dig into one player’s stats and rating history, and search for upcoming tournaments, all straight from the official US Chess database.
Paste a PGN and step through the game on a board. Moves are read by matching against the legal moves, so a wrong file is caught rather than replayed.
Checkmate Pattern QuizTwelve mating patterns, one move each. The answers are found by search rather than stored, so what you are told cannot disagree with the board.
Chess Board Vision TrainerFive drills for the things strong players never have to look up — square colours, coordinates, knight distances, and what a piece hits from where it stands.
FEN Position BuilderSet up any chess position and get its FEN, or paste a FEN and see the board. Checks for positions that are well-formed but impossible.
Chess960 Position GeneratorGenerate any of the 960 Fischer random starting positions by number, with the board drawn and the placement rules explained.
Chess ClockA real two-sided chess clock with increment, both delay styles and multi-period tournament controls. Tap your own side to end your move.
US Chess Tournament HelperCompare two US Chess members through their shared opponents, look up rated histories and find events — plus why a handful of common games proves nothing.
Chess960 (Fischer Random)Play Chess960 against the computer, with proper Fischer Random castling — including the king that swaps places with its own rook.
About these chess tools
A rating is a measurement rather than a property, and the Elo system says something precise about what it measures. A 200-point gap predicts that the stronger player scores about 76 per cent — not 76 per cent of games won, but 76 per cent of available points, with draws counting half. A 400-point gap predicts about 91 per cent. The formula behind this is a logistic curve, which has a consequence worth sitting with: no gap, however large, predicts certainty. A 600-point underdog is still expected to take around five per cent of the points, so an upset is not evidence that the ratings were wrong. It is the system working as designed. The second thing worth knowing is that ratings from different pools are not comparable. A national federation rating, an online rapid rating and an online blitz rating are three separate scales that happen to use similar numbers, and they can differ by hundreds of points for the same player without anything being amiss, because each is calibrated only against the population it was earned in. Comparing them directly is the commonest mistake people make with chess numbers. The third is that rating change is driven entirely by the gap, not by how well you played. Beating someone 300 points below you gains almost nothing and losing to them costs a great deal, because the system measures surprise rather than quality. That asymmetry is why strong players avoid weak fields, and why a rating climbs fastest when a player is consistently underrated for their current strength — the number always lags the player, in both directions.