A screenshot is the cleanest picture of a chess position you can get: straight, sharp and without reflections. ChessWOW reads the board from the image, places every piece on an analysis board and lets Stockfish 19 calculate the position on your device. This guide shows how to do it, how to get a clean result and what to check before you trust the engine.
Where useful screenshots come from
Most positions worth a second look arrive as images. A friend sends a puzzle in a group chat. A chess video pauses on a position the commentator skips over. A coach shares a study as a picture. You finished a game and saved the final position. A website shows a diagram without a way to copy it. In all of these cases, typing the position by hand takes minutes and is easy to get wrong. A scan takes a few seconds, and you only need to check the result.
How to analyze a screenshot in three steps
- Step 1
Choose the image. Open ChessWOW and tap "Scan position". Pick the screenshot from your photo library, or paste an image you copied. On a Mac, the same two options work: Photos or the clipboard.
- Step 2
Check the board. The recognized position appears as a board next to your image. Compare the two. Squares the recognition is unsure about are marked. Tap a square to change or remove a piece, and set whose move it is.
- Step 3
Read the analysis. Stockfish 19 starts right away. You see the evaluation, the best move as an arrow and up to three lines. Play a move on the board and the engine recalculates.
Tips for a clean recognition
- Show the whole board. All 64 squares must be visible. Crop away browser bars or chat bubbles if they cover an edge of the board, but do not crop into the board itself.
- Avoid overlays. Arrows, colored squares and move highlights drawn on top of the board can hide pieces. If possible, take the screenshot without them.
- Check the orientation. If Black is at the bottom of the image, use "Flip board" so the squares match. The app warns you when the orientation looks uncertain.
- Larger is better. A screenshot from a tablet or computer has more pixels per square than a small preview image. If you only have a thumbnail, open it full size first.
- Rotated photo? If the image is sideways, rotate it in steps of 90 degrees. The corner markers rotate with it.
What a picture cannot tell you
A screenshot shows where the pieces stand. It does not show whose move it is, whether a king or rook has moved before, or whether the last move was a pawn advancing two squares. These details change the analysis: a position can be winning for the side to move and losing for the other. ChessWOW therefore asks you to set the side to move and lets you confirm castling rights and en passant only when you know they apply. If the position is impossible, for example a side without a king or a pawn on the first rank, the app tells you what is wrong before the engine starts.
After the scan
The scanned position is a normal analysis board. You can explore your own ideas and jump back at any time, copy the position as FEN to use it elsewhere, or play it out against Stockfish at one of five levels. Every scan is saved in your library, so you can come back to a puzzle later and compare your solution with the engine. The guide on the offline Stockfish app explains how to read the evaluation.
Your images stay on your device
Recognition and analysis run entirely on your iPhone, iPad or Mac. The screenshot is not uploaded to us or anyone else, and you do not need an account. For pictures taken with the camera, for example of a computer screen, see the scan guide on the home page. For printed diagrams, see scan a chess book diagram.
Questions and answers
Which screenshots work best?
Screenshots of 2D boards from apps, websites and videos, with the whole board visible and no arrows drawn on top. Straight screenshots are more reliable than photos of a screen.
Can I paste an image instead of saving it first?
Yes. Copy the image in another app and paste it in the scanner.
Why do I have to choose whose move it is?
A picture does not show it, and the best move depends on it. ChessWOW asks so the analysis is for the right side.
What if one piece is wrong?
Tap the square and pick the correct piece. Uncertain squares are marked to help you find mistakes quickly.
Can I get the FEN of a screenshot?
Yes. After the scan, copy the position as FEN and paste it into any other chess program.
Is my screenshot uploaded?
No. Recognition runs on your device and the image is not sent anywhere.
Continue with
Scan the next puzzle someone sends you.
ChessWOW runs on iPhone, iPad and Mac. No account needed.
Download free