How to Batch Convert Images for Free on Windows

Batch image conversion — converting, resizing, or reformatting a folder full of images at once — is one of those tasks that sounds like it should be simple but somehow always ends up taking longer than expected. Online converters work for one or two images but fall apart at scale. Paid tools like Adobe Bridge are overkill. The correct answer is two free desktop tools that have handled this reliably for years: IrfanView and XnConvert.

Tool Comparison

Method 1: IrfanView Batch Conversion

IrfanView (irfanview.com) is a lightweight image viewer that includes a powerful batch processing feature. Install the full package with plugins to ensure maximum format support.

Steps

1. Open IrfanView. In the menu, go to File → Batch Conversion/Rename (or press B).
2. In the "Input files" section on the left, navigate to your folder and add files. Use Ctrl+A to select all, or drag and drop files directly into the window. The file list appears on the right.
3. Under "Batch conversion settings," choose your output format from the dropdown (JPEG, PNG, WebP, BMP, TIFF, and dozens more).
4. For JPEG output, click Options to set the quality level. 85 is a good balance of quality and file size.
5. Set the output directory. Check Use this directory as output and browse to where you want the converted files saved. Always output to a different folder than your originals — this prevents accidental overwrites.
6. Optionally check Use advanced options to resize images, rotate them, adjust colors, or add a text overlay as part of the batch.
7. Click Start Batch. IrfanView processes the files and shows a log of completed conversions.

Method 2: XnConvert for Multi-Step Actions

XnConvert (xnview.com/en/xnconvert) handles more complex scenarios: stripping EXIF data while resizing and converting format in a single pass, adding watermarks, applying color corrections, or converting RAW files. Its action-based pipeline is more flexible than IrfanView for multi-step tasks.

Steps

1. Open XnConvert. On the Input tab, click the folder icon or drag your image files onto the window.
2. Switch to the Actions tab. Click Add action to build your processing pipeline. Common actions include:
   • Image → Resize: Set target dimensions or percentage. Choose "Fit within" to preserve aspect ratio.
   • Image → Canvas: Add borders or padding.
   • Metadata → Set EXIF/IPTC/XMP: Clear all metadata before sharing photos online.
   • Miscellaneous → Add watermark text: Stamp images with a text overlay.
3. Switch to the Output tab. Select your format from the dropdown. Each format has its own settings button for quality, compression level, and color space options.
4. Set the output folder. Check "Delete original files" only if you are certain the conversion worked correctly — run a small test batch first.
5. Click Convert. A progress bar shows each file being processed.

Format Guidance

• PNG to JPEG: Good for photos where you do not need transparency. JPEG at 85 quality is typically 60–80% smaller than the equivalent PNG for photographs.
• JPEG to PNG: Only makes sense when you need transparency or when you need to preserve text/graphic quality. Re-encoding a JPEG to PNG does not recover quality lost in the original JPEG compression.
• Any format to WebP: WebP is 25–35% smaller than JPEG at equivalent quality, and supported by all modern browsers. Useful for website assets.
• Camera RAW to JPEG/DNG: Both IrfanView (with RAW plugin) and XnConvert handle common RAW formats. For serious RAW work, RawTherapee (free) or darktable (free) are more appropriate.

For simple format-conversion jobs, IrfanView is faster to set up. For anything involving multiple processing steps, metadata stripping, or watermarking, XnConvert is worth the slightly higher setup time. Both are free, portable, and handle thousands of images without issues.