Free · Stockfish 18 · In your browser
Your move first. Ours when you ask.
The Chess Calculator is a set of quiet chess tools. Nothing runs when a page loads. You set up the position, you think, and when you want a second opinion you ask for one. Then the answer is the largest thing on the page.
Stockfish 18 runs inside this tab. Free, no login, and the position never leaves your browser.
Best move
Your move first.
Find best moveNothing is evaluated until you ask.
Best move for White
Forces Nxb8, then Rd8 is mate.
Pick the help you need
Each tool answers one question about one position. Start from what is in front of you. More tools arrive over time, and every one of them follows the same rule.
When you are stuck on one position
Best move calculator
Paste a FEN, a PGN, or a game link, or set the board. Ask, and get the best move, the evaluation, two alternatives, and the reason the engine likes its pick.
Free · No loginWhen The Password Game asks for a move
Best move in algebraic chess notation
Rebuild the rule 16 diagram on an empty board, pick whose move it is, and copy the one move to paste, written like Qd5+.
Free · No loginWhen you want to find it yourself first
Pathwise
Play your move on one board. The engine plays its move on a second board only after you commit, then a plain-language note explains the difference. No undo, you play on from your own choice.
Free · No loginWhen your rating needs to make sense elsewhere
Rating converter
Convert between Chess.com, Lichess, USCF, and FIDE rating points, with the method and the date the table was last updated printed on the page.
Coming soon
Help is something you ask for
Most engines start talking the moment a board appears. Coaches have said for years that this is backwards: form your own idea first, then check it. Every tool here is built around that order.
- 01
Set up the question
Paste a FEN, a PGN, or a public Chess.com or Lichess game link, or place the pieces by hand. Nothing is evaluated while you build the position.
- 02
Think it through
No eval bar, no arrows, and no best move on a position you have not asked about. Pick your own candidate first. That is the part that makes you better.
- 03
Ask, and read one answer
Press Find best move. The move comes back in the largest type on the page, with the evaluation, two alternatives, and one sentence on why.
The rule every tool follows
Written down so it holds as the site grows. If a tool here ever breaks one of these, that is a bug.
- 01The engine loads in the background, but it does not search until you ask.
- 02No arrows, no eval bar, and no answer on a position you have not asked about.
- 03Once you ask, the answer is the largest thing on the page, followed by one sentence on why.
- 04Nothing you paste leaves the tab. No account, no daily cap, no ads.
- 05Bad input is named, not silently repaired into a different position.
- 06Not for live games. Using an engine during a rated game is cheating. Use these tools after the game, or on a study position.
What runs when you ask
Stockfish 18 Lite with its NNUE network is compiled to WebAssembly and served from this domain. Your browser downloads it once, then searches to depth 18 locally and reports three candidate moves. There is no server doing the thinking, which is why a position you paste is never uploaded.