Resize Images
Resize images online by exact pixels or percentage, with aspect-ratio lock to prevent distortion. Free batch resizing, private, fast, no uploads required.
Up to 50 images · max 50 MB each · nothing leaves your device
About This Tool
Change the dimensions of your images quickly and precisely. Resize by exact pixel values or by percentage, with an optional aspect ratio lock to prevent distortion. Process entire batches of images at once, ideal for preparing photos for websites, social media, or email. Everything runs in your browser with zero uploads and zero quality loss beyond what you choose.
How To Use
- Drop your images into the upload zone or click to select files from your device.
- Choose to resize by pixels or percentage, and enter your desired dimensions.
- Toggle the aspect ratio lock on or off depending on your needs.
- Click "Resize" and download your resized images individually or as a ZIP.
How It Works
Image resizing works by creating a new canvas at your target dimensions and drawing the original image onto it using high-quality bicubic interpolation built into the browser's Canvas API. When the aspect ratio lock is enabled, changing one dimension automatically calculates the other to maintain the original proportions.
For percentage-based resizing, we multiply the original width and height by your chosen scale factor. A 50% resize on a 4000×3000 image produces a 2000×1500 result. For pixel-based resizing with aspect lock, we fit the image within your specified dimensions while maintaining proportions, similar to CSS "contain" behavior.
The entire operation happens inside a Web Worker using OffscreenCanvas, so your browser stays completely responsive. Each image is processed sequentially to keep memory usage low, which is especially important on mobile devices where a decoded 20MP photo can consume 80MB of RAM. After processing, the resized canvas is encoded back to your original format at maximum quality.
Frequently Asked Questions
Does resizing reduce image quality?
Downscaling (making images smaller) is virtually lossless because the browser uses high-quality interpolation. Upscaling beyond 200% can introduce visible blurriness since new pixels must be invented from existing data.
Can I resize multiple images to the same dimensions?
Yes, batch processing applies the same resize settings to all images at once. All files in your batch will be resized to the exact same dimensions or percentage that you specify.
What happens to the aspect ratio?
With aspect ratio lock enabled (default), changing width automatically adjusts height proportionally, and vice versa. Turn it off if you need to stretch or squash an image to exact dimensions.
Is there a maximum image size?
Each file can be up to 50MB. The maximum output dimensions are 10,000 pixels on each side. Very large images may take a moment to process but your browser will handle them without issues.
What output format do I get?
The output matches your input format. JPEG in, JPEG out. PNG stays PNG. This preserves transparency for PNG images and keeps JPEG files compact without unnecessary format conversion.
Are my images sent to a server?
No. Resizing happens entirely in your browser using the Canvas API. Your images stay on your device at all times. The tool works perfectly even without an internet connection after the page loads.