You have 30 photos that all need to be resized, converted, or compressed — individually uploading each one to a web tool would take all afternoon. Or maybe you're on a company computer where you can't install anything. Here's a practical breakdown of options that don't require installing software, from built-in OS tools to browser-based workflows.
What's already built into Windows
Windows has more image-processing capability than most people realize, hidden in right-click menus and built-in apps.
- Resize multiple photos at once: Select multiple images in File Explorer → right-click → "Resize pictures" (if you've installed the free PowerToys utility from Microsoft — highly recommended, it adds this and many other useful tools). Without PowerToys, you can resize images in the Photos app, but only one at a time.
- Convert to PDF: Select multiple images → right-click → "Print" → choose "Microsoft Print to PDF" as the printer → this creates a PDF with one image per page. Crude, but works for a quick job.
- Basic editing: The built-in Paint app can open, crop, resize, and save images. It supports JPG, PNG, BMP, GIF, and TIFF — not WebP or HEIC without additional codecs.
What's already built into macOS
Mac users have powerful batch tools without installing anything:
- Preview batch resize and convert: Open multiple images in Preview simultaneously (select them all in Finder, then Open). Go to Edit → Select All, then Tools → Adjust Size to resize all at once. For format conversion, go to File → Export Selected Images, pick the format (JPG, PNG, PDF, TIFF, etc.) and destination — done in seconds for any number of files.
- Automator workflows: The built-in Automator app can create repeatable workflows for batch image tasks — resize to a specific size, convert format, rename files, add watermarks. Steep learning curve but very powerful once set up.
- Quick Actions: Right-click multiple image files in Finder → Quick Actions → you'll find convert image and create PDF options.
Browser-based batch options
Several browser tools accept multiple files at once. The FileSwift JPG-to-PDF tool, for example, accepts multiple images dropped at once and combines them into a single PDF — which is itself a form of batch processing. The Merge PDF tool similarly handles multiple files at once.
For truly large batches (100+ images that each need individual processing), browser tools become impractical — you'll want a desktop solution. But for smaller jobs of 5–20 files, browser tools are often the fastest path precisely because there's no installation, no license, and no version to keep updated.
Free desktop tools worth installing
If you're doing this regularly enough that browser tools feel slow, a few lightweight free desktop tools are worth knowing:
- IrfanView (Windows): Tiny, fast, and does batch conversion, resize, rename, and format conversion for hundreds of files at once. The batch dialog is under File → Batch Conversion/Rename.
- XnConvert (Windows/Mac/Linux): Purpose-built for batch image conversion with a proper GUI. Accepts dozens of input formats, exports to many output formats, supports multiple simultaneous operations.
- ImageMagick (command-line, all platforms): Extremely powerful, can process thousands of images with a single command, but requires comfort with a terminal. The learning curve is steep; the capability is essentially unlimited.
When to use what
- Single file that needs processing right now → browser tool, no download.
- A handful of files (2–10) → browser tool if it accepts multiple, or built-in OS tools.
- Dozens of files of the same type → built-in OS batch tools (Preview on Mac, PowerToys on Windows).
- Hundreds of files or a repeatable workflow → IrfanView, XnConvert, or ImageMagick.