Batch Resize Hundreds of Images in the Browser — Full Guide

To resize dozens or hundreds of images at once, use Zro7 Batch Resize Images. Drop a folder, pick a strategy (fit-width, fit-height, longest-edge, or exact dimensions), and every file is resized in parallel across worker threads — then delivered as a ZIP. All in your browser.

Resize modes that don't crop

• Longest-edge — the safest default. "Longest edge = 1600px" keeps aspect ratios and normalizes mixed portrait/landscape sets.
• Fit width — good for blog assets: every image ends up exactly 1200 px wide, heights vary.
• Exact — pad or crop to hit a target dimension (e.g. 1080×1080 for Instagram).

Why do it in the browser

• No upload wait — 300 raw phone photos would take 20 minutes to upload to a SaaS.
• No file-count cap — free web tools usually stop at 10.
• Runs on your CPU cores in parallel; a modern laptop resizes 500 photos in under a minute.
• Nothing sensitive leaves the device — helpful for medical, legal, or client photography.

Steps

1. Open Batch Resize Images.
2. Drop a folder of images.
3. Pick a resize mode and target dimensions.
4. Choose output format (keep original, or convert everything to WebP/JPEG for smaller files).
5. Click Resize all and download the ZIP.

Pair with compression

Resizing shrinks pixel count; compression shrinks bytes per pixel. Do both: resize to 1600 px longest-edge, then compress with Compress Image at MozJPEG 80. A 4 MB DSLR photo becomes a 200 KB web asset with no visible loss.