Updated 27 August 2026
What is a chess best move calculator?
A chess best move calculator takes a position and returns the move an engine would play, with an evaluation. This one runs Stockfish 18 in your browser. Paste a FEN or set the pieces on the board. The move it names is the answer; the number beside it is White's score in pawns at the depth shown.
Here for rule 16 of the Password Game? Use the best move in algebraic chess notation page. It starts from an empty board so you can copy the picture.
How to get the next best move
Paste a position or try a puzzle. The best move appears as soon as Stockfish has one. Read the two alternatives when they fill in.
- Paste a FEN, a PGN, or a Chess.com or Lichess game link, or set the position on the board.
- Read the best move as soon as it appears. It firms up as the depth climbs.
- If two moves look close, play the one you understand.
Ways to import a position
A FEN is a one-line snapshot of the board; a PGN is a game or a move list. Paste either, or a public Chess.com or Lichess game link, and Stockfish runs in this tab. Private games stay on those sites. Photo import is coming soon.
FEN
A one-line snapshot of the board: pieces, side to move, castling, and the move counters.
On Lichess, open the board menu and copy FEN. On Chess.com, Share then Copy FEN. Analysis boards show the same string. Paste it here.
PGN
A game record or a move list. Analysis starts on the last move.
On Chess.com, Share then PGN. On Lichess, the download menu exports a PGN. You can also paste a move list such as 1. e4 e5, or upload a .pgn file.
Chess.com
A public game link, or recent games from a Chess.com username.
Open the finished game. Copy the URL in the address bar, or Share then Copy link. It looks like chess.com/game/live/…. Private games stay on Chess.com.
Lichess
A public game link, or recent games from a Lichess username.
Open the game. Copy the URL in the address bar, or use Share. It looks like lichess.org/abcdefgh. Unlisted games cannot be fetched.
PhotoSoon
Reading a board from a screenshot is not available yet.
Not available yet. Import a FEN, a PGN, or a public game link instead.
What the evaluation number means
The evaluation is White's score in pawns. +1.40 means White is about a pawn and a half better, even if it is Black to move. Negative numbers favor Black. It is not a prediction of the result. It is the engine's claim about the position at the end of the best line it searched.
- ±0.30 is level. A +0.18 is not an advantage worth playing for; that is the usual club-player misread.
- 0.50 to 1.50 means one side has something real.
- Past 2.00 is usually winning with accurate play.
- Past 5.00 is decided.
- +M4 is mate in four for White, with no pawn score.
Why the same position can show two different evals
Depth is how many half-moves the engine looked ahead. An eval without a depth is meaningless. The same position can read +0.20 at depth 8 and −1.90 at depth 24, once a tactic three moves deeper comes into view.
The move on the page is live. You do not wait for depth 18. Depth 8 is already a useful club-player answer; deeper looks catch longer tactics. The number next to the eval is the depth you actually got.
On a phone the search stops after a few seconds so the page does not sit there thinking. A laptop usually reaches depth 18. The depth is always shown, so you are never looking at a number without knowing how far Stockfish looked.
How to read the best line
The first move in the line is the best move. The rest is the sequence Stockfish expects if both sides keep playing the best replies. The evaluation belongs to the end of that line, not to the position on the board. Play the line out before you argue with the number.
Trust the first two or three moves. The tail is a guess, and it will change as depth rises.
If line 2 is close to line 1, the position has two good moves. Play the one you understand. If the second line would give the game away, the best move is the only move. The other lines are there to show what you would throw away.
Engine docs call this the principal variation, or PV. The 3 lines come from asking Stockfish to keep 3 candidates, not one.
What happens when the FEN is messy
A FEN copied from chat often has trailing spaces. A FEN after a double pawn push may carry an en passant square the side to move cannot use. A study position may never have occurred in a real game. All of those are legal things to analyze. A lot of calculators break on them anyway.
This one trims whitespace, fills in missing move counters, drops an impossible en passant square, and tells you what it repaired. If the position is actually illegal, a ninth square on a rank, a missing king, it names the problem. It will not analyze a different position in silence.
Best move calculator compared
How this page differs from Lichess analysis, Chess.com, and NextChessMove.
| Feature | This page | Lichess analysis | Chess.com | NextChessMove |
|---|---|---|---|---|
| Engine | Stockfish 18 in this browser | Stockfish on Lichess servers | Chess.com engine, account for saved analysis | Stockfish on their servers |
| Login | None | None for analysis | Account for saved games | None for the free tool |
| Position leaves this device | No, except when you import a public game | Yes | Yes | Yes |
| What you get | Best move, eval, three lines, a plain-language why | Full analysis board | Game review and engine lines | One move and an eval |
| Input | Board, FEN, PGN, or a game link | Board, PGN, or URL on Lichess | Your games | FEN and PGN on their site |
Is this chess calculator free?
Yes. The best-move calculator is free, with no login and no cap on how many positions you analyze. Stockfish 18 runs in this browser tab. You do not create an account, and there is no move pack to buy. If paid coaching is added later, this calculator stays free.
Does my position get uploaded?
A FEN you paste and the pieces you drag stay in this tab. If you import a Chess.com or Lichess game, we fetch the public PGN from that site so Stockfish can run here. We do not keep a copy of the game after that.
What is a FEN?
A FEN is a one-line snapshot of a chess position: pieces, side to move, castling, en passant, and the move counters. Lichess copies one from the board menu. Chess.com copies one from Share, Copy FEN. Import that string, or import a PGN or a public game link instead.
What is a PGN?
A PGN is a game written as moves, often with player names and a result. Chess.com copies one from Share, PGN. Lichess exports one from the download menu. You can also paste a move list such as 1. e4 e5, or upload a .pgn file. Analysis starts on the last move. Step back with previous.
How do I import a Chess.com or Lichess game?
Open the finished game and copy the URL from the address bar, or use Share then Copy link. A Chess.com live game looks like chess.com/game/live/…. A Lichess game looks like lichess.org/abcdefgh. We fetch the public PGN so Stockfish can run here. Private games stay on those sites. You can also paste a username and fetch recent public games.
Why did the search stop before depth 18 on my phone?
A phone cannot finish depth 18 in a middlegame without sitting there for minutes. The search stops after a few seconds and shows the depth it reached. The move on screen is live from the first look; you do not wait for the bar to fill.
Why did the best move change when I used more threads?
Stockfish on more than one thread shares a hash table. Two runs of the same position can return different moves at the same depth, because the search is no longer deterministic. Use 1 thread when you need the same answer every time. Use more threads when you only care about a faster first look.
Is using a best move calculator cheating?
In a rated game, yes. Using an engine while you play is cheating on Chess.com, Lichess, and over the board under FIDE rules. Use this page on a study position, a puzzle you already finished, or a game after it ended. If you are still playing, close the tab.