The Image Resizer changes the dimensions of images to specific pixel sizes or percentage scales directly in your browser. Upload any JPEG, PNG, WebP, or GIF image and enter the target width, height, or percentage. By default, the aspect ratio is locked so the image does not become distorted: enter a width and the height is calculated automatically to maintain proportions, and vice versa. Unlock the aspect ratio to set both dimensions independently if you need a specific canvas size. Preset sizes are available for common social media dimensions and device resolutions. Output format can be JPEG (with quality control) or PNG. All processing uses the HTML5 Canvas API and runs locally in your browser, your images are never sent to any server. For complete results, Image Compressor can reduce image file size without quality loss, QR Code Generator can generate QR codes for URLs, text, and contact data, and Image to Base64 can convert images to Base64 data URIs for inline embedding.
Image resizing is one of the most frequent image operations for web developers, content creators, and social media managers. For web performance, serving images at the exact size they will be displayed (rather than relying on the browser to scale them down) significantly reduces bandwidth usage and improves Core Web Vitals scores. An image that will be displayed at 400x300 pixels but is uploaded at 2400x1800 pixels wastes 36 times the bandwidth. Modern responsive web design uses the srcset attribute to serve different image sizes to different screen resolutions, but this requires preparing the different sizes first. For social media platforms, correct image dimensions prevent auto-cropping by the platform, which often removes important parts of the composition. Twitter/X crops to 16:9 on timeline cards, Instagram crops to 1:1 or 4:5 in the feed, and LinkedIn crops to 1.91:1 for link previews. Resizing to the correct dimensions before uploading ensures your image displays as intended. For email marketing, images wider than 600 pixels may overflow the email container in Outlook and other desktop clients that do not constrain image width to the column width. Resizing hero images to exactly 600px width before embedding in HTML emails prevents this layout issue. The percentage resizing option is useful when you need to proportionally reduce a batch of images to a fraction of their original size without knowing the exact pixel dimensions in advance.
Read our guide: In-depth guide for Image Resizer