Image Resizer
Resize one or multiple JPG, PNG, and WEBP images directly in your browser. Files are processed locally without being uploaded to a server.
Drag and drop one or more images here, or choose files
Supported formats: JPG, PNG, WEBP
Resize Settings
When enabled, the tool preserves each image's original ratio. For batch resizing, the last edited side is treated as the main value.
Download resized files separately through your browser.
Original Files (0)
Resized Results (0)
About this image resizer
This tool lets you resize one or multiple images directly in your browser.
If aspect ratio lock is enabled, each image keeps its own original proportions during batch resizing.
After resizing, you can download files one by one or all together as a ZIP file.
FAQ
Can I resize multiple images at once?
Yes. You can upload multiple files and resize them together using the same settings.
What happens when I lock the aspect ratio?
The tool preserves each image's original proportions. In batch mode, the last edited side is used as the main value.
Can resizing increase file size?
Yes. File size does not always decrease after resizing. It depends on the output dimensions, original format, and browser encoding.
How Image Resizing Works
This tool resizes images using the HTML Canvas API with pixel resampling. When you upload an image, it is decoded into a bitmap and drawn onto a canvas element set to your target dimensions. The browser's 2D rendering context applies bilinear or bicubic interpolation — depending on the implementation — to calculate new pixel values for each position in the output grid. Downscaling blends neighboring source pixels into fewer output pixels, preserving overall color accuracy while reducing fine detail. Upscaling extrapolates new pixel values between existing ones, which is why enlarging a small image beyond its natural resolution produces a soft or blurry result.
The resizer supports three input modes: explicit pixel dimensions (width × height), a scale percentage, and a longest-side constraint for batch normalization. When you lock the aspect ratio, the tool calculates the missing dimension automatically so your images never become distorted. After resampling, the canvas serializes the output as a JPEG or PNG Blob using the toBlob API and delivers it as a browser download. No frames of your image are ever sent to a remote server — the entire pipeline runs inside the JavaScript sandbox.
When to Use the Image Resizer
- 1Resizing product images to a standard size (e.g., 800 × 800 px) before bulk-uploading to an e-commerce platform — most platforms require a consistent aspect ratio and reject oversized files.
- 2Creating responsive image variants for a web page — prepare a 1200 px wide version for desktops and a 600 px wide version for mobile without re-exporting from design software.
- 3Preparing avatar or profile photos for platforms with strict upload dimension requirements, such as 400 × 400 px for LinkedIn or 150 × 150 px for forum icons.
- 4Reducing the resolution of scanned documents or photographs before sharing by email or uploading to a slow connection — a 6000 × 4000 px photo resized to 1920 × 1280 px is typically 5–8× smaller.
Dimension & Quality Guide
For web use, 1200–1920 px wide is sufficient for full-width images. Going above 2000 px rarely improves perceived sharpness on standard screens but significantly increases file size and load time.
For retina / HiDPI displays, prepare images at 2× the CSS display size. A 600 px CSS image should have a 1200 px source file for sharp rendering on retina screens.
Avoid upscaling more than 150 % — the interpolation algorithm cannot invent detail that was not in the original, and the result will appear soft or pixelated on close inspection.
When downscaling by more than 50 % in a single step, consider two-step downsizing (e.g., 4000 px → 2000 px → 1000 px). Some browsers' canvas interpolation produces slightly sharper results with incremental steps.
Supported Formats & Browser Compatibility
- Supported input formats: JPEG (.jpg, .jpeg), PNG (.png), WebP (.webp), GIF (.gif, first frame only), BMP (.bmp).
- Output format: JPEG or PNG, selectable per file. JPEG is recommended for photographs (smaller); PNG for graphics and images requiring transparency.
- Browser support: Chrome 60+, Edge 79+, Firefox 55+, Safari 13+. WebP input requires Safari 14+. All modern mobile browsers are supported.
- There is no file size restriction beyond the device's available RAM. Very large images (above 30 MP) may be slow to process on mobile devices.
Tips for Best Results
Tip 1
Always lock the aspect ratio unless you intentionally want to distort the image — a mismatched width and height creates stretched content that looks unprofessional.
Tip 2
Use the percentage mode for quick scaling: 50 % halves both dimensions and produces a file roughly one-quarter the original area, significantly reducing file size.
Tip 3
For batch resizing to a standard longest side (e.g., 1200 px), use the longest-side constraint mode — both landscape and portrait images will be normalized correctly.
Tip 4
After resizing, run the image through the compressor tool to further reduce file size — canvas-output JPEG files are not automatically compressed at the maximum ratio.
Tip 5
For print output, keep resolution at 300 DPI: a 4-inch wide print needs 1200 px, a 6-inch print needs 1800 px. Resizing for screen and resizing for print require different target dimensions.
Tip 6
When preparing images for social media, check each platform's current recommended dimensions — they change and can vary by post type, story, or cover photo.
Help
Frequently Asked Questions
Does resizing happen on the server?
No. Resizing uses the HTML Canvas API inside your browser. Your images are processed entirely on your device and never transmitted to any server.
Will resizing reduce the file size?
Downscaling almost always reduces file size significantly because there are fewer pixels to encode. However, the canvas output is not the most aggressively compressed encoding — run the result through the compressor for the smallest possible file.
Can I resize an image to a larger size than the original?
Yes, but upscaling beyond the original resolution will produce a soft or blurry result because the interpolation algorithm cannot create detail that was not present in the source.
How do I resize without distorting the image?
Enable the aspect ratio lock. When you enter a new width, the height is calculated automatically to maintain the original proportions.
Can I resize multiple images at once?
Yes. Select multiple files in the picker. Each file is resized to the specified dimensions independently. Batch mode uses the same settings for all files.
What happens to transparency when I resize a PNG?
Transparency is preserved when you keep the output format as PNG. If you switch output to JPEG, transparent areas are filled with a solid background color.
Why does my resized image look blurry?
Blurriness is a natural result of downscaling with interpolation. For the sharpest results, avoid downscaling by more than 50 % in a single step, and ensure the source image is sharp to begin with.
Is there a maximum image dimension supported?
The Canvas API has a maximum dimension limit that varies by browser — typically 16,384 × 16,384 px in Chrome and Firefox. Images larger than this will fail to load into the canvas. Most cameras produce images well within this limit.