Image Resizer
ここに画像をドロップ
またはクリックして選択 (JPEG, PNG, WebP)
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About Image Resizer
The Image Resizer is a free browser-based image scaling utility designed to instantly solve the frustrating problem of images being rejected for being too large when creating blog thumbnails, posting to social media platforms like X (formerly Twitter) or Instagram, or uploading documents for online certification exams.
Modern smartphone cameras produce photos with resolutions of several thousand pixels and file sizes of 3-5 MB or more. Embedding these directly into blog posts significantly slows down page loading speed, which negatively impacts both SEO and user experience. This tool lets you drag and drop oversized images to quickly convert them to optimized sizes.
The tool supports diverse scenarios: setting the width to exactly 1200 pixels, setting height to 800 pixels while maintaining aspect ratio, or shrinking to exactly 50% of the original size. It offers two input methods—direct pixel value entry for precise dimensions, and an intuitive percentage slider for quick adjustments. The "Maintain Aspect Ratio" checkbox prevents distortion and ensures beautiful proportions.
Critically, no uploaded image data is ever sent to external servers. All resizing calculations are performed locally using your browser's built-in HTML5 Canvas capabilities. This means work-related confidential materials and personal photos are processed with complete privacy—there is absolutely no risk of data interception or server-side leakage, making this a highly secure tool you can trust for any purpose.
How to use Image Resizer
- Drag and drop your image file (JPG, PNG, WebP) into the central area or click to select.
- Choose your resize method: Pixels (for precise dimensions) or Percentage (for proportional scaling).
- Enable aspect ratio lock or skip-if-smaller options as needed.
- Adjust output quality using the slider (80% recommended) and select your desired format.
- Click "Convert & Download" to get your resized images instantly.
Benefits of Image Resizer
- Flexible Dual Resize Modes - Choose precise pixel input for exact dimensions like 1200×630px (OGP format), or use intuitive percentage scaling for roughly 50% reduction. Both methods are available to match your specific needs.
- Built-in Aspect Ratio Lock - Prevents common distortion mistakes by automatically calculating the second dimension when you specify one. Photos maintain their original proportions without manual height/width adjustment.
- 100% Local Processing & Privacy - All resizing happens entirely in your browser using HTML5 Canvas. No server uploads, no data transmission, no leakage risk. Process confidential files or personal photos with complete peace of mind.
- Batch Processing with ZIP Export - Select and resize multiple images simultaneously, with automatic ZIP compression for efficient download. Handle large projects in one go.
- Multi-Format Support (JPEG/PNG/WebP) with Quality Control - Customize output format and quality settings. 80% quality is recommended for optimal file size and visual quality balance.
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