About
The Chess Calculator is an independent site of free chess tools. Each one answers a single question about a single position, runs the engine in your browser, and asks for nothing in return.
What we make
A tool here takes a position, does exactly one job with it, and shows the answer in the largest type on the page. The first one is the best move calculator: give it a position and it names the move, the evaluation, two alternatives, and the reason.
The site is deliberately narrow. It is not a chess server, a training course, or a game database. If you want to play a game, there are better places. If you want a straight answer about the position in front of you, this is the site.
How it works
The engine runs in your tab
Stockfish 18 Lite with its NNUE evaluation network is compiled to WebAssembly and served from this domain rather than a third-party CDN. Your browser downloads it once and then runs the search locally, at depth 18, reporting three candidate moves. Nothing about the position travels to a server, which is why the site can promise that positions are not uploaded and still be telling the truth.
Why the headers are strict
Serving the engine ourselves is also why the site sets cross-origin isolation headers. Those headers are what let the browser hand out the shared memory that multi-threaded Stockfish needs. When a browser will not grant isolation, the single-threaded build runs instead and the answer is the same, just slower.
What we believe
- The answer belongs at the top, in the biggest type, before any explanation.
- Bad input should be named, not silently repaired into a different position.
- A number without a sentence is a wasted number, so every evaluation gets a plain-language reason.
- A tool that needs a login to answer one question is asking for too much.
Who runs it
The Chess Calculator is built and maintained by a single independent developer. It is funded by nobody, sells nothing, and has no paid tier. If that changes, it will say so on this page first.
Contact
Questions, bug reports, and position disagreements go to hello@thechesscalculator.com. There is more detail on the contact page, and the data practice is written out on the privacy page.