Image Resizer
Resize images in your browser with custom dimensions, aspect ratio lock, and batch processing. All processing is client-side.
About This Tool
The Image Resizer is a free, browser-based tool that lets you change the dimensions of PNG, JPEG, WebP, and GIF images without installing any software. Whether you need to prepare images for a website, social media, email, or app icons, this tool handles it quickly and privately.
All resizing is performed entirely on your device using the HTML5
Canvas API. When you upload an image, it is read into memory via
URL.createObjectURL,
drawn onto an off-screen
element at your specified dimensions, and then exported using
canvas.toBlob()
with your chosen MIME type and quality level. No data ever leaves
your browser.
The aspect ratio lock feature ensures your images are never distorted. When enabled, changing one dimension automatically calculates the other to maintain the original proportions. You can also choose from common preset sizes like 1920x1080 (Full HD), 1280x720 (HD), 800x600, and square formats including 256x256, 128x128, and 64x64 for icons and thumbnails.
The output format selector lets you convert between PNG, JPEG, and WebP during the resize. For JPEG and WebP, a quality slider controls the lossy compression ratio, letting you balance image quality against file size. The results panel shows a side-by-side comparison of the original and resized images with file size statistics so you can see exactly how much space you saved.
For larger workflows, Batch Mode lets you upload multiple images and resize them all to the same dimensions in one operation. Each file is processed individually with its own status indicator, and you can download resized files individually or all at once. This is ideal for preparing product images, generating thumbnail sets, or standardizing image sizes across a project.
How to Use
- Drag and drop an image onto the upload area, or click it to browse your files. Supported formats are PNG, JPEG, WebP, and GIF.
- The original image preview, file size, and dimensions are displayed automatically. The width and height fields are pre-filled with the original dimensions.
- Adjust the Width and Height fields to set your desired output dimensions. With the aspect ratio lock enabled, changing one value updates the other proportionally.
- Optionally select a Preset Size from the dropdown to quickly apply common dimensions like Full HD, Square 256, or Square 64.
- Choose an Output Format (PNG, JPEG, or WebP) and adjust the Quality slider for JPEG and WebP outputs.
- Click Resize (or press Ctrl+Enter ) to process the image. The resized preview and size comparison will appear.
- Click Download to save the resized image. Use Copy Stats (or Ctrl+Shift+C ) to copy the size comparison text.
FAQ
Which image formats are supported?
The Image Resizer supports PNG, JPEG, WebP, and GIF input files. You can export the resized image as PNG, JPEG, or WebP. GIF animations are flattened to a single frame during resizing since the Canvas API does not preserve animation frames.
Is my image data kept private?
Yes. All image processing happens entirely in your browser using the HTML5 Canvas API. Your images are never uploaded to any server. There are no network requests, no cookies, and no third-party analytics on your image data. You can use this tool offline after the page has loaded.
What is the maximum file size I can resize?
The tool accepts images up to 50 MB. Very large images or high-resolution photos may take a few seconds to process depending on your device hardware. For the smoothest experience, images under 10 MB are recommended.
How does the aspect ratio lock work?
When the aspect ratio lock is enabled (the lock icon), changing the width automatically recalculates the height proportionally, and vice versa. This prevents your image from being stretched or squished. Click the lock icon to toggle it off if you need non-proportional dimensions.
Does the quality slider affect PNG output?
No. PNG is a lossless format, so the quality parameter is ignored by the browser Canvas API when exporting as PNG. The quality slider only applies to JPEG and WebP output formats. To reduce PNG file size, resize the image to smaller dimensions or switch to WebP format.
Can I resize multiple images at once?
Yes. Switch to Batch Mode using the toggle at the top. You can drag and drop or browse for multiple images. Set your desired width, height, format, and quality, then click Resize All. Each file is processed individually, and you can download them one by one or all at once.
Why does resizing sometimes increase the file size?
This can happen when converting from a highly compressed lossy format to a lossless one (e.g., a small JPEG to PNG), or when exporting at very high quality settings. If you need a smaller file, try lowering the quality slider, choosing JPEG or WebP as the output format, or reducing the target dimensions.
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