Free Image Resizer
Resize any image without uploading it anywhere. Drag and drop your JPG, PNG, or WebP file and resize by exact pixels, percentage scale, or max dimension (fit within a box). Lock the aspect ratio to avoid distortion, choose output format (JPG, PNG, WebP), set compression quality, preview before and after side by side, and download instantly.
Drop an image here, or click to browse
Supports JPG, PNG, WebP, GIF · All processing is in your browser
All resizing happens locally in your browser using the Canvas API — your images are never uploaded to any server.
Frequently Asked Questions
What image formats does this tool support?+
You can upload JPG, PNG, WebP, and GIF files. Output formats are JPG, PNG, and WebP. Note: GIF animation is not preserved — animated GIFs are converted to a static image of the first frame. For PNG files, quality settings don't apply (PNG is lossless); quality only affects JPG and WebP output.
What does "aspect ratio lock" do?+
When aspect ratio is locked, changing the width automatically adjusts the height proportionally (and vice versa), so the image is scaled without distortion. For example, a 1200×800 image has an aspect ratio of 3:2. If you change the width to 600px, the height automatically becomes 400px. Unlock the ratio to resize width and height independently, which will stretch or squish the image.
What is the "Max Dimension" resize mode?+
Max Dimension resizes the image to fit within a square bounding box of the specified size, preserving the original aspect ratio. For example, setting max dimension to 1920px will scale a 3000×2000 image to 1920×1280 (constrained by the 1920px width), and a 2000×3000 image to 1280×1920 (constrained by the 1920px height). It will never upscale an image that is already smaller than the specified dimension.
Is it safe to resize images here?+
Yes. All processing happens locally in your browser using the HTML5 Canvas API. Your image is never uploaded to any server. Nothing leaves your device — you can even use this tool with no internet connection after the page loads.
What quality setting should I use for JPG and WebP?+
For web use, 75–85% quality is the sweet spot: excellent visual quality with significantly smaller file sizes than 100%. For professional print work, use 90–95%. Anything above 95% produces rapidly diminishing returns in quality but much larger files. WebP typically produces smaller files than JPG at the same visual quality, so you can often use 80% WebP and get a smaller file than 90% JPG.
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Image Resizing — Pixels, Aspect Ratio, and Format Choice
When you resize an image, you are telling the browser's Canvas API to redraw the image's pixel grid at a new resolution. This tool uses imageSmoothingQuality: 'high' on the 2D canvas context, which applies a higher-quality interpolation algorithm compared to the default, resulting in sharper downsampled images with less aliasing.
Choosing the Right Output Format
JPG — Best for photographs and complex images with gradients. Lossy compression: some detail is discarded to reduce file size. At 80–85% quality the visual difference from 100% is barely noticeable, but file sizes are 60–70% smaller. PNG — Best for images with sharp edges, text, logos, or transparency. Lossless: every pixel is preserved exactly. PNG files are generally larger than JPG for photographic content. WebP — Google's modern format, supported by all major browsers. Produces files 25–35% smaller than JPG at equivalent visual quality. Recommended for web publishing.
Standard Image Dimensions for Common Use Cases
Social media profile photo: 400×400px. Twitter/X header: 1500×500px. Facebook cover: 851×315px. Instagram post: 1080×1080px. Full HD background: 1920×1080px. 4K wallpaper: 3840×2160px. Blog post featured image: 1200×630px (Open Graph size). Thumbnail: 150×150px or 300×300px. Email header: 600×200px. For web performance, always resize images to the display size before publishing — serving a 4000px image displayed at 400px wastes bandwidth and slows page load.