What image formats are supported?

This tool supports all common web image formats including JPG/JPEG, PNG, GIF, WebP, and BMP. The output is always PNG for maximum quality.

Image Resizer - Free Online Image Resize Tool (2025)

How Image Resizing Works

This tool uses HTML5 Canvas API to resize images directly in your browser. No server upload means faster processing and complete privacy.

Key Features:
• Client-Side Processing: Your images never leave your device
• Aspect Ratio Lock: Automatically maintains proportions
• Instant Download: Get resized images immediately
• Format Support: JPG, PNG, GIF, WebP, BMP

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Expert Tip: Downsize, Don't Upsize

Always resize DOWN, never UP. Enlarging images creates blurry, pixelated results. If you need larger images, use the highest resolution source available or use AI upscaling tools.

Common Mistakes

Upsizing Images: Enlarging images beyond their original size reduces quality and creates pixelation.
Wrong Aspect Ratio: Unlocking the ratio can distort images. Keep it locked unless you intentionally want to stretch/squeeze.
Using Low-Quality Sources: Resizing can't improve a bad source image. Always start with the highest quality available.

Reviewed by Sarah Martinez, Graphic Designer

Updated November 26, 2025

Frequently Asked Questions

How do I resize an image without losing quality?

To minimize quality loss, only downsize images (never upsize). Use formats like PNG for graphics and JPEG with 85-95% quality for photos. Our tool processes images in your browser without compression.

Does this tool upload my images to a server?

No, all image processing happens locally in your browser using HTML5 Canvas. Your images never leave your device, ensuring complete privacy.

How do I maintain aspect ratio when resizing?

Keep the 'Lock Ratio' checkbox checked. When you change width, the height will automatically adjust proportionally (and vice versa) to maintain the original aspect ratio.

What is the maximum image size I can resize?

There's no strict limit, but performance depends on your device. Most browsers can handle images up to 10,000x10,000 pixels. Very large images may take longer to process.