Chess Calculator
Find your best next move instantly with the most powerful chess calculator. Stockfish 18 engine, AI coaching, undetectable Human Mode, and live board scanning — all in your browser.
Now powered by the latest Stockfish 18 (released January 2026).
“Don't just see the best move — understand why it's best. AI coaching that teaches you to think like a stronger player.”
Find your best move instantly — works on any device, no download needed
How to Use the Chess Calculator
Hint
Get the engine's best move instantly with evaluation
AIvsAI
Watch two engines battle and see how the strongest moves play out
AutoMe
Automatically play the best moves for your side (toggle on/off, or press Space)
Undo
Take back the last move played
Reset
Start a fresh game from the beginning
Flip
Rotate the board to play from other side
Turn
Change whose turn it is to move
Kings
Clear board and keep only the kings
ELO Slider PREMIUM
Train at different levels — beginner (600) to grandmaster (3650)
Human Mode (No Ban) PREMIUM
Undetectable moves that look human — opponents can't tell you're using an engine
Screenshot Scanner PREMIUM
Screenshot any position from any site or app — auto-detect pieces and analyze instantly
FEN & PGN PREMIUM
Import any game or position — paste FEN/PGN and analyze instantly
Smart Tactics PREMIUM
Train your tactical eye. Choose a pattern and the engine finds positions where that tactic works.
Brilliant PREMIUM
Find sacrifice patterns that lead to forced checkmate.
Smother PREMIUM
Learn smothered mate — knight checkmate where king is trapped.
Queen Hunt PREMIUM
Target the queen with coordinated piece play.
Fork PREMIUM
Practice double-attack patterns.
Promote PREMIUM
Find the fastest path to promote your pawn and win.
Trap PREMIUM
Restrict piece mobility to win material.
Draw PREMIUM
Learn defensive techniques to save difficult positions.
Stalemate PREMIUM
Recognize positions where no legal moves remain.
AI vs AI PREMIUM
Watch two engines battle at any speed.
Why Use Chess Calculator?
Chess Calculator doesn't just show you the best move — it teaches you whyit's best. The AI Coach breaks down every position into tactics, strategy, and principles you can apply in your own games.
With 11 AI bots from 400 to 3650 ELO, Smart Tactics training, Human Mode with undetectable moves, and a Screenshot Scanner that reads any board instantly — Chess Calculator gives you every advantage.
Powered by Stockfish 18
Stockfish 18 is the world's strongest open-source chess engine, rated over 3500 ELO — more than 600 points stronger than any human player. It uses NNUE neural network evaluation combined with deep alpha-beta search, analyzing millions of positions per second. Chess Calculator runs Stockfish 18 directly in your browser via WebAssembly — no download, no server calls, instant analysis.
Frequently Asked Questions
What is Chess Calculator and how is it different?
Chess Calculator is a free online chess analysis tool powered by Stockfish 18. Unlike basic move finders, it includes an AI Coach that explains why moves are best, 11 AI bots for practice games, Smart Tactics training with 9 tactical patterns, and a Screenshot Scanner that scans screenshots. Everything runs in your browser — no download needed.
How accurate is the Stockfish 18 engine?
Stockfish 18 is rated over 3500 ELO on the CCRL rating list, making it the strongest chess engine available. It's over 600 points stronger than Magnus Carlsen's peak rating of 2882. The engine uses NNUE neural network evaluation for position assessment and deep alpha-beta search for move calculation.
Can I analyze my online games here?
Yes. Export your game as PGN from any chess platform, then paste it into Chess Calculator. The engine evaluates every move, identifies mistakes and brilliant moves, and the AI Coach explains key moments. You can also paste a FEN string to analyze any specific position.
What is the AI Coach and how does it work?
The AI Coach provides natural-language explanations for every position. After you make a move or request a hint, the coach explains the tactics, strategy, and chess principles behind the engine's recommendation. It's available in 19 languages and helps you understand chess thinking, not just memorize moves.
Is Chess Calculator completely free?
Yes, the free tier includes position analysis up to 800 ELO depth, 5 AI coaching insights per day, all 11 AI bots, and the full interactive board. Premium (from $19.99) unlocks 3650 ELO depth, unlimited AI coaching, Human Mode (No Ban), Smart Tactics, Screenshot Scanner, and full PGN game analysis.
What devices does Chess Calculator work on?
Chess Calculator works on any device with a modern web browser — desktop, laptop, tablet, or phone. The Stockfish engine runs via WebAssembly directly in your browser, so there's nothing to install. We also offer a desktop app for macOS and Windows with 20x faster offline analysis.