Free Chess Analysis Tool & Move Calculator | ChessAlgo
ChessAlgo is a free chess move calculator powered by Stockfish — the world’s strongest open-source chess engine. Paste any FEN string, set up any position, and get engine-level analysis in seconds. No login. No paywalls. Just chess.
Every tool a serious player needs.
Post-game review, opening prep, endgame drill, puzzle training — ChessAlgo’s chess move calculator handles the analysis so you can focus on learning the why behind every move.
Best Move Finder
Enter any position — or paste a FEN directly — and get the engine’s top recommended move with an evaluation score. Stockfish calculates at depth 20 by default, giving you the same analysis strength top grandmasters use in preparation.
Core FeaturePosition Evaluation
That “+0.3” number isn’t just a score — it’s a story. ChessAlgo translates engine evaluations into clear language so you understand whether the position is equal, slightly better, or completely lost. No chess degree required.
Clarity FirstFEN String Analysis
Copy any FEN string from Chess.com, Lichess, or your own PGN file and paste it straight into ChessAlgo. Any legal chess position from opening to endgame loads instantly. No manual setup, no piece dragging required.
Paste & AnalyzeEngine Line Preview
See not just the best move, but the whole continuation — the line of play Stockfish predicts several moves deep. This is how you train your calculation: you see the machine’s logic, then compare it to yours.
Study DeepVariable Analysis Depth
Quick blunder check? Use depth 12 and get an answer in under a second. Serious opening prep? Crank it to depth 24 and let Stockfish go deep. You control the depth — and the quality of insight — depending on what you need.
Flexible DepthWorks Anywhere
Fully browser-based. No download. No app. No plugin. Whether you’re on a laptop reviewing last night’s game or on your phone during a lunch break, ChessAlgo loads fast and runs clean on any device.
Zero FrictionFrom game to analysis in 30 seconds.
ChessAlgo is designed to remove every bit of friction between you and engine insight. Here’s exactly how it works.
Open the Chess Move Calculator
Head to the ChessAlgo calculator page. The board loads immediately with the standard starting position. No login, no loading screen, no nonsense.
Set Up Your Position
You’ve got two options: drag and drop pieces to recreate your game position manually, or paste a FEN string directly into the input field. FEN strings from Lichess, Chess.com, or any PGN tool work perfectly.
Choose Your Analysis Depth
Select how deep you want Stockfish to calculate. Depth 15 is great for a quick blunder check. Depth 22+ is for serious prep work where you want the engine to really dig in.
Find the Best Move
Hit “Find Best Move.” Stockfish runs the analysis and returns the top move, the evaluation score, and the engine continuation line — everything you need to understand the position deeply.
Study the Line and Improve
This is where the real learning happens. Compare Stockfish’s recommendation to the move you played. If they differ, ask yourself why. That gap is where chess improvement lives.
position: “r1bqkbnr/pppp1ppp/2n5/4p3/4P3/5N2/PPPP1PPP/RNBQKB1R w KQkq – 2 3”
depth: 20
to_move: “white”
// Running Stockfish analysis…
analyzing: ████████████ 100%
What does +0.3 actually mean?
The chess engine evaluation score is the single most important number in analysis — and the most misunderstood. Here’s a plain-English breakdown you’ll actually remember.
Stockfish measures position evaluation in centipawns — where 100 centipawns equals roughly one pawn of advantage. A score of +0.3 means White has an advantage worth about one-third of a pawn. That’s a tiny edge. A score of +3.0 means White is effectively up a full bishop or knight.
Positive numbers always mean White is better. Negative numbers mean Black is better. Zero means the position is dead equal — a true balance of forces that, in theory, should end in a draw with perfect play from both sides.
The engine evaluation gets more dramatic fast. Scores above +5 or below -5 typically indicate a position that’s already decided — the rest is technique. Mate-in-X scores (M1, M2, etc.) mean the engine has found a forced checkmate sequence regardless of the opponent’s defense.
Built for every kind of chess learner.
Whether you’re a casual player reviewing a weekend game or a club player prepping for a serious tournament, ChessAlgo gives you engine-level insight without the complexity.
Post-Game Review
You just finished a game online. You know something went wrong around move 22, but you can’t figure out exactly where. Copy the FEN from that critical position, paste it into ChessAlgo, and let Stockfish show you what should have happened — and why.
Opening Preparation
Testing a new line in the Sicilian Defense? Curious whether that early queen sortie really is as bad as your coach says? Use ChessAlgo to verify opening theory against the engine. You’ll see evaluation scores for every critical branch.
Endgame Training
Endgames are where games are won and lost — and where most club players have the biggest gaps. Set up any endgame scenario and see exactly how Stockfish handles it. The precision is humbling and educational.
Puzzle Creation & Verification
Chess coaches and content creators use ChessAlgo to verify that a tactical puzzle has exactly one best solution — and that the solution is as clean as they think it is. Paste the FEN, run the analysis, and confirm your puzzle at depth 20+.
Why use ChessAlgo over other tools?
There are other ways to analyze chess positions. Here’s a direct comparison of what matters most for study and analysis.
| Feature | ChessAlgo | Lichess Analysis | Chess.com Analysis |
|---|---|---|---|
| Free to use | ✓ Always free | ✓ Free | ~ Limited free |
| Account required | ✓ No account | ~ Optional | ✗ Required |
| FEN string input | ✓ Yes | ✓ Yes | ✓ Yes |
| Engine | ✓ Stockfish | ✓ Stockfish | ✓ Komodo |
| Adjustable depth | ✓ Yes | ~ Limited | ✗ Fixed tiers |
| Distraction-free UI | ✓ Clean & focused | ~ Feature-heavy | ✗ Ad-heavy |
| Study-first design | ✓ Yes | ~ Mixed | ✗ Game-focused |
Get the most from engine analysis.
Using a chess engine the right way is a skill in itself. These are the study habits that separate players who improve from those who just watch numbers move.
Guess Before You Look
Before running analysis on a position, commit to a candidate move. Write it down if you have to. Then run Stockfish. The difference between your move and the engine move is exactly the lesson you need to study.
Study the Why, Not Just the What
Stockfish says Nf3 is better than Ne2. Great — but why? Look at the engine continuation line, 4-5 moves deep. What does each piece do? What tactics does it enable?
Use High Depth for Critical Positions
For most casual review, depth 15–18 is perfectly adequate. But for critical positions — the moment a game turned, a key tactical puzzle, an endgame that should be winning — push depth to 22 or higher.
Review Blunders Systematically
Pick the three biggest mistakes from any game and study each one in isolation using ChessAlgo’s FEN input. Quality of review beats quantity every time at the club level.
Test Alternative Defenses
Run analysis on a position where you played poorly, then ask: what if you’d played a different move? This “what if” analysis is how you build opening and middlegame knowledge that sticks.
Don’t Over-Rely on the Engine
Use ChessAlgo to check your analysis, not replace it. Form your own view, then consult the engine. Over time, your views will start to align — and that’s when you know you’re genuinely getting better.
Key terms every chess analyzer should know.
New to engine analysis? These are the terms that come up most often when using a chess move calculator or reviewing engine lines.
What chess players say about ChessAlgo.
The FEN input alone is worth it. I pull critical positions from my Lichess games, paste them in, and have Stockfish’s take in seconds. My review sessions are genuinely faster and sharper than before.
I use ChessAlgo to verify puzzles I create for my students. It’s the cleanest FEN-to-analysis tool I’ve found. No account needed, no clutter. Depth 22 gives me exactly the confirmation I need.
I’m a beginner trying to understand why I keep losing the middlegame. ChessAlgo’s evaluation score explained in plain terms helped me finally understand what positional advantage means.
Everything you want to know about chess analysis.
Answers to the most common questions about chess move calculators, engine analysis, Stockfish, and how ChessAlgo works.
What is ChessAlgo’s Chess Move Calculator?
Is ChessAlgo’s Chess Move Calculator completely free?
How do I paste a FEN position into ChessAlgo?
Does ChessAlgo work on mobile phones and tablets?
What chess engine does ChessAlgo use?
What does the +/- number mean in chess engine evaluation?
Is using a chess engine during a game cheating?
What Is a Chess Move Calculator?
A chess move calculator is a software tool that uses a chess engine — typically Stockfish, Komodo, or Leela Chess Zero — to evaluate any given chess position and recommend the strongest available move.
ChessAlgo’s free chess move calculator runs Stockfish natively in your browser using WebAssembly technology. This means analysis happens locally on your device without needing a server connection — results are fast, private, and always available.
How Does Stockfish Find the Best Chess Move?
Stockfish uses a combination of alpha-beta pruning, iterative deepening, and NNUE neural network evaluation. The result is an engine that consistently identifies the strongest human-playable moves and detects tactical threats invisible to most players below grandmaster level.
Chess Position Analysis vs. Chess Move Calculator: What’s the Difference?
A chess move calculator focuses on the immediate best move in a given position. A chess position analyzer provides broader context: evaluation trends, multiple candidate moves, alternative lines, and strategic themes.
Free Chess Engine Analysis: What to Expect
Free chess engine tools have improved dramatically since 2020. Browser-based Stockfish via WebAssembly now delivers analysis at depth 20+ directly in Chrome, Firefox, and Safari — without requiring an account or paid subscription.
Ready to find your best move?
Open ChessAlgo’s free chess move calculator and get Stockfish-powered analysis of any position — no login, no limits, no cost.