Resize Images for GitHub README Files
Images in GitHub README files should be sized for the markdown container (typically 700-900px wide) and optimized for fast loading. Oversized images slow down page rendering and waste bandwidth for every visitor. ImageGates resizes your screenshots and diagrams to GitHub-optimal dimensions.
Image sizes for GitHub README files
GitHub renders README content in a column about 900 px wide on desktop and scales images down to fit. Anything wider is downscaled by the browser, and screenshots of code suffer most from that resample.
Exact specifications:
- Maximum useful width: 900 px (README column)
- Retina-crisp screenshots: 1800 px wide, displayed at 900
- Social preview card: 1280×640 px (2:1)
- Per-file upload ceiling: 10 MB via drag-and-drop
- Formats: PNG for UI and code, SVG for diagrams, GIF for demos
What causes a rejected or degraded result:
- Committing 4 MB screenshots into the repository, which every clone then downloads.
- Using JPG for terminal or code screenshots — text edges become blotchy.
- Hard-coding a width in HTML that breaks the mobile layout instead of using a resized file.
Preparation order that avoids rework:
- Capture at 2× and resize the longest side to 1800 px.
- Export PNG for interfaces, SVG for architecture diagrams.
- Compress before committing; a 200 KB screenshot is normally indistinguishable from a 2 MB one.
How to use this tool
- Upload image — Select your screenshot, diagram, or banner for the README.
- Resize to 800-1200px — Resize to fit GitHub's markdown container width.
- Add to README — Download and reference in your README.md file.
Guide
Well-sized images in GitHub READMEs improve project documentation and user experience. Every visitor to your repository loads these images, so optimization matters.
GitHub image best practices: - Resize to 800-1200px wide (matches container) - Use PNG for screenshots with text - Use JPG for photographic content - Use SVG for diagrams and logos - Keep total image weight under 5MB per README - Use GitHub's image hosting (drag-drop into issues)
README image types: 1. Project logo/banner (top of README) 2. Screenshots of the application 3. Architecture diagrams 4. Demo GIFs (keep under 5MB) 5. Badge images (auto-generated, no optimization needed)
Frequently asked questions
What image width should I use for GitHub READMEs?
GitHub's markdown container is about 888px wide. Upload images at 800-1200px wide for crisp display. Larger images are auto-scaled and waste bandwidth.
What format is best for GitHub images?
PNG for screenshots and diagrams (sharp text). JPG for photographs. SVG for logos and simple graphics. GIF for short demos.
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