Image Resizer

How Browser Image Resizing Works

ConvertUnlimited uses the HTML5 Canvas API to resize your images directly in your browser. When you add a file, your browser decodes the image data into RAM. When you specify new dimensions, the browser's graphics engine draws that image onto a canvas of the new size, applying interpolation algorithms to maintain visual clarity.

Because all calculations happen on your device's CPU and GPU, your images are not intentionally uploaded by this tool. This local-first approach ensures local browser-based processing and supports batch processing of large photo sets.

Resizing vs. Compression

While both techniques reduce file size, they work differently:

• Resizing changes the physical dimensions (pixel width and height) of the image. This is ideal for meeting specific requirement for websites, social media, or email attachments.
• Compression reduces the data size while keeping the same dimensions by optimizing how the color data is stored.

Our tool allows you to do both simultaneously by adjusting the dimensions and the output quality slider.

Understanding Aspect Ratio

The "Lock Aspect Ratio" feature ensures your image doesn't look stretched or squashed. When enabled, changing the width will automatically calculate the correct height based on the original image's proportions (and vice versa). If you need exact specific dimensions that don't match the original shape, uncheck this box, but be aware it may distort the image.

Best Practices for Image Sizing

Choosing the right size is crucial for web performance. Here are some common standards:

• Website Heroes: 1920px to 2560px width.
• Blog Posts: 800px to 1200px width.
• Social Media Posts: Usually 1080px to 1200px square or portrait.
• Thumbnails: 150px to 300px width.

Always try to resize your images to the exact size they will be displayed on screen to achieve the fastest loading times and best SEO scores (Core Web Vitals).

Privacy & No-Upload Model

Most "online" tools are actually cloud-based, meaning your files are sent to their disks. ConvertUnlimited is different. We provide the logic as a static script that runs in your local environment. Your data stays under your control at all times, making it safe for sensitive documents, personal photos, and corporate assets.

Batch Resizing Tips

• Memory Management: If you are resizing 100+ high-resolution photos, your browser may temporarily slow down. For the smoothest experience, process images in batches of 20-50.
• ZIP Downloads: After processing a batch, use the "Download All (ZIP)" button to bundle all your resized images into one organized file.
• Format Choice: Use WebP for the best balance of small size and high quality on modern websites. Use JPG for maximum compatibility with older software.

Frequently Asked Questions

Is there a file size limit?

We don't impose a software limit, but very large images (e.g., 50MB+ RAW exports) may exceed your browser's allocated memory. If a tab crashes, try processing fewer files at once.

Will my images lose quality?

Downscaling (making an image smaller) always involves some data loss, but modern browser interpolation makes this nearly imperceptible. Upscaling (making an image larger) will likely result in blurriness.

Can I convert formats while resizing?

Yes. You can upload a PNG and export it as a resized WebP or JPG directly using the format selector.