Image Resizer

How to Use the Image Resizer

This free online image resizer lets you change image dimensions directly in your browser using the HTML5 Canvas API. Upload any image file (JPEG, PNG, WebP, GIF), set your desired width and height, and download the resized result as a PNG file. All processing happens client-side, so your images are never uploaded to any server, ensuring complete privacy and instant results.

Aspect Ratio Lock

By default, the aspect ratio lock is enabled. When you change either the width or height, the other dimension is automatically calculated to maintain the original proportions. This prevents your image from being stretched or distorted. Uncheck the lock if you need to set custom dimensions independently, for example when creating images for specific social media requirements or banner sizes that differ from the original aspect ratio.

Common Use Cases

Image resizing is essential for web development, social media posting, email attachments, and document preparation. Different platforms require specific image dimensions: Instagram posts work best at 1080x1080 pixels, Twitter headers at 1500x500, and Facebook covers at 820x312. Resizing images before uploading them reduces page load times and bandwidth usage. For e-commerce sites, consistent product image dimensions create a professional, uniform appearance across your catalog.

Quality Considerations

Upscaling (making images larger) may result in pixelation since new pixel data must be interpolated. For best quality, resize images to smaller dimensions or stay close to the original size. The tool outputs PNG format which is lossless, preserving quality during the resize operation. For photographs where file size matters more than pixel-perfect quality, consider using the Image Compressor tool after resizing.

Image Resizerの使い方

このツールはブラウザ上で動作する無料の画像リサイズツールです。画像をアップロードし、幅と高さをピクセル単位で指定してリサイズできます。アスペクト比ロック機能により、画像の縦横比を維持したままサイズ変更が可能です。処理はすべてクライアントサイドで行われ、PNG形式でダウンロードできます。