How to Convert a Diagram Screenshot to Mermaid Code

You have a diagram screenshot — maybe from a whiteboard session, a PDF, or a legacy tool — and you need it as editable code. Converting an image to Mermaid code by hand means squinting at arrows, retyping labels, and debugging syntax for half an hour. There's a faster way.

ImageToMermaid uses AI-powered image recognition to analyze your diagram screenshot and generate clean, editable Mermaid.js code in seconds. This guide walks through the full conversion flow.

What Is Mermaid.js?

Mermaid is a text-based diagramming language that renders flowcharts, sequence diagrams, ER diagrams, and more from simple markup. It's supported natively in GitHub, GitLab, Notion, and dozens of documentation tools. Instead of dragging boxes in a GUI, you write code like this:

flowchart LR
    A[User uploads image] --> B[AI analyzes diagram]
    B --> C[Mermaid code generated]
    C --> D[Edit in live editor]

The advantage: your diagrams live in version control, diff cleanly, and can be regenerated anywhere Mermaid is supported.

Step 1: Upload Your Diagram

Open the ImageToMermaid app and upload your diagram image. Supported formats include PNG, JPG, and WebP. You can drag and drop, click to browse, or paste from your clipboard.

For best results, use a clear screenshot with readable text labels. The AI handles hand-drawn diagrams, but clean digital screenshots produce the most accurate output.

Step 2: AI Analysis

Once uploaded, GPT-4o analyzes the image and identifies the diagram type — flowchart, sequence diagram, ER diagram, class diagram, or others. It extracts nodes, relationships, labels, and directional flow.

The AI returns structured output including:

• diagram_type — the detected Mermaid diagram type
• mermaid_code — the generated Mermaid syntax
• confidence — how confident the AI is in its interpretation

Most conversions complete in under 10 seconds.

Step 3: Edit in the Live Editor

The generated Mermaid code loads into a Monaco editor (the same editor that powers VS Code) with syntax highlighting and autocompletion. A live preview renders beside it, updating as you type.

Common edits after conversion:

• Renaming node labels for clarity
• Adjusting arrow directions (e.g., LR to TD)
• Adding missing connections the AI didn't detect
• Changing node shapes (square [], round (), diamond {})

Step 4: Export and Use

Once you're happy with the diagram, you have several options:

• Copy the code — paste it into GitHub READMEs, Notion pages, or documentation that supports Mermaid
• Download as PNG — use the Mermaid to PNG tool for image export
• Share the code — Mermaid syntax is plain text, so it diffs and reviews like any other code

Tips for Better Conversions

A few things that improve AI accuracy:

• Crop tightly — remove unnecessary whitespace and surrounding UI from your screenshot
• Use readable text — if labels are blurry or tiny, the AI may misread them
• One diagram per image — the AI works best when there's a single diagram to interpret
• Standard diagram types — flowcharts and sequence diagrams convert most reliably; very complex or non-standard layouts may need manual cleanup

Which Diagrams Work Best?

The AI handles all Mermaid-supported diagram types, but accuracy varies:

• Flowcharts — excellent accuracy, especially with standard shapes and clear arrows
• Sequence diagrams — very good with clearly labeled actors and messages
• ER diagrams — good, though complex cardinality notation sometimes needs manual correction
• Class diagrams — good for standard UML class boxes
• Gantt charts, pie charts, mindmaps — reasonable, but these are often easier to write from scratch

If you're new to Mermaid syntax and want a quick reference for manual edits, check out the Mermaid Syntax Cheat Sheet.

Try It Yourself

Upload a diagram screenshot and get editable Mermaid code in seconds. Try ImageToMermaid free — no account required for your first conversions.