Image Resizer – Resize Images Online Free
Image Resizer is a free online tool that resizes JPG, PNG, WebP, and GIF images to any dimension using the HTML5 Canvas API — no upload, no server, no software to install. Choose custom pixel dimensions with optional aspect-ratio lock, or pick from presets for HD, 4K, Instagram, Twitter, and Facebook. Output as JPG, PNG, or WebP.
Your files never leave your device. All resizing is done locally using the Canvas API. No upload, no server, no storage.
How to Resize Images Online Free
- 01
Upload your image
Drag and drop or click to upload a JPG, PNG, WebP, or GIF. The original dimensions and file size are shown immediately.
- 02
Set dimensions or pick a preset
Enter custom width and height values (aspect ratio lock keeps proportions), or choose a social media preset from the dropdown.
- 03
Resize and download
Click "Resize Image" to process using the Canvas API, preview the result, then click Download. Nothing is uploaded anywhere.
Features
- ✓Custom width & height in pixels
- ✓Aspect ratio lock (auto-calculates the other dimension)
- ✓8 social media presets (Instagram, Twitter, Facebook…)
- ✓Output as JPG, PNG, or WebP
- ✓Quality slider for JPG and WebP (1–100)
- ✓Drag & drop upload
- ✓100% client-side — Canvas API, no server
- ✓No login, no file upload, no sign-up
Frequently Asked Questions
How does browser-based image resizing work?
The tool draws your image onto an HTML5 Canvas element at the target dimensions using the Canvas API's drawImage method, then exports the canvas to a Blob using toBlob(). No library is needed and nothing is sent to a server — all processing happens inside your browser tab.
Will resizing an image reduce its quality?
Upscaling (making an image larger than the original) always reduces sharpness because the browser must interpolate new pixels. Downscaling generally preserves quality well. For JPG and WebP output, the quality slider (default 90) controls compression — lower values reduce file size but add compression artefacts.
What does the aspect ratio lock do?
When the lock is enabled, changing either the width or height automatically recalculates the other dimension to preserve the original proportions. Disable the lock to set width and height independently and crop the image to a specific ratio.
Which social media presets are available?
The presets cover the most common platforms: HD (1280×720), Full HD (1920×1080), 4K (3840×2160), Instagram Square (1080×1080), Instagram Story (1080×1920), Twitter Post (1200×675), Facebook Cover (820×312), and Thumbnail (150×150).
Is there a file size or dimension limit?
There is no enforced limit, but very large images (above 30 MP) may strain browser memory and slow down processing. If you experience issues, consider compressing the image first using the Image Compressor tool, then resizing.