How to Batch Convert Hundreds of Images at Once
The Problem
You have 500 HEIC photos from your iPhone that need to be JPG. Or 200 PNGs that need to be WebP for your website. Or a folder of MIX formats that all need to be standardized. Converting one at a time would take hours. Batch conversion handles them all at once.
Method 1: CocoConvert (Online)
Upload up to 50 files at once on CocoConvert. Select the target format and quality, click Convert All, and download the results as a ZIP file. The conversion happens in your browser, so files stay private. For more than 50 files, run multiple batches. This is the fastest method that doesn't require installing software.
Method 2: macOS Preview
Select all images in Finder, right-click → Open With → Preview. In Preview, select all thumbnails (Cmd+A), then File → Export Selected Images. Choose your target format and quality, pick a destination folder, and export. Preview handles JPG, PNG, TIFF, HEIC, and WebP. It's surprisingly powerful for batch operations.
Method 3: IrfanView (Windows, Free)
Download IrfanView (free for personal use). Go to File → Batch Conversion/Rename. Add your files, select the output format, choose a destination, and click Start Batch. IrfanView can also resize, rename, and adjust quality during the batch process. It handles basically every image format in existence and processes thousands of files quickly.
Method 4: Command Line
For developers and power users: ImageMagick (cross-platform) converts any image format. Example: mogrify -format jpg *.heic converts all HEIC files in a folder to JPG. For WebP: for f in *.png; do cwebp '$f' -o '${f%.png}.webp'; done. FFmpeg handles video batch conversion similarly. The command line is the fastest option for truly large batches (thousands of files).
Tips for Large Batches
Size your expectations: 1,000 high-res images can take 10-30 minutes depending on the method. Free up disk space — you need room for both originals and converted files. Don't delete originals until you've verified the converted files look correct. Use consistent naming — batch rename during conversion if your tool supports it. Start with a small test batch (10 files) to verify settings before processing everything.