Free Online Chess Analysis Tool - Stockfish Game Analyzer
Chess It UpPGN Input
Best Move
Top Moves
Accuracy
Summary
How to Use This Free Chess Analyzer
Step 1: Import Your Chess.com or Lichess Games
Enter your username from Chess.com or Lichess to instantly load your recent games. You can also paste PGN notation directly from any source. Our analyzer supports all standard PGN formats including games with clock times, annotations, and multiple variations.
Step 2: Run Stockfish NNUE Analysis
Click "Full Game Analysis" to run our Stockfish engine powered by NNUE (Efficiently Updatable Neural Network). The engine evaluates every position at configurable depth, calculating millions of positions to find the best moves. Free users get depth 12 analysis, while premium subscribers can analyze at depth 25 for even more accurate evaluations.
Step 3: Review Move Classifications
Every move is classified based on centipawn loss - the difference between your move and the engine's best move. Classifications include: Brilliant (!!), Great Move (!), Best Move, Good, Inaccuracy (?!), Mistake (?), and Blunder (??). Understanding these classifications helps identify patterns in your play.
Step 4: Study the Evaluation Bar & Best Lines
The evaluation bar shows the position assessment in centipawns or mate-in-X. Positive values favor White, negative favor Black. Click any move to see the engine's recommended continuation with visual arrows. This helps you understand not just what was wrong, but what you should have played instead.
Step 5: Track Your Accuracy & Improve
After analysis, review your accuracy percentage and average centipawn loss (ACPL). Lower ACPL means more accurate play. Compare your accuracy between time controls - are you better at rapid or blitz? Use these metrics to track improvement over time and identify which phase of the game (opening, middlegame, endgame) needs the most work.
Why Chess It Up for Free Chess Analysis?
Unlimited Free Game Reviews
Unlike Chess.com which limits free users to 1 game review per day, Chess It Up provides unlimited analysis. Analyze your bullet games, blitz battles, rapid matches, and daily chess - all completely free.
Professional-Grade Stockfish Engine
We use the latest Stockfish with NNUE evaluation, the same engine that consistently ranks #1 in computer chess championships. Get grandmaster-level analysis without paying premium subscription fees.
Instant PGN Import & Export
Import games from any source using standard PGN format. Export your analyzed games with engine annotations to study offline, share with coaches, or import into other chess software.
Opening Book Integration
See when you leave established opening theory. The analyzer identifies book moves and shows where you or your opponent first deviated, helping you build a stronger opening repertoire.
Frequently Asked Questions
What is centipawn loss and why does it matter?
Centipawn loss measures how much your move differed from the engine's best move. One centipawn equals 1/100th of a pawn. If the best move evaluates to +1.50 and you played a move that evaluates to +1.00, your centipawn loss is 50. Lower average centipawn loss (ACPL) indicates more accurate play. Strong players typically average 20-40 centipawn loss per game.
How does Stockfish NNUE differ from classical Stockfish?
NNUE (Efficiently Updatable Neural Network) is a neural network evaluation that replaced Stockfish's classical hand-crafted evaluation in 2020. NNUE evaluates positions more accurately, especially in complex middlegames and endgames. It's roughly 80-100 Elo stronger than classical Stockfish while maintaining fast calculation speeds.
What engine depth should I use for analysis?
Depth 8-10 is sufficient for most analysis and catches virtually all tactical mistakes. Higher depths (12+) help in complex endgames and quiet positions where subtle positional factors matter. Premium users can analyze at higher depths for more nuanced evaluations, but free depth 12 analysis is more than adequate for learning.
Can I analyze games from other platforms besides Chess.com and Lichess?
Yes! While we have direct integration with Chess.com and Lichess usernames, you can analyze games from any platform by pasting the PGN directly. This includes games from Chess24, ICC, FIDE Online Arena, or even your own over-the-board games that you've recorded.