Can't convert jpg to webp with the preview app

WebP is a modern image format developed by Google that offers superior compression compared to JPG while maintaining excellent quality. Converting JPG to WebP can significantly reduce file sizes, making websites load faster and saving storage space. On a Mac or Windows, there are several ways to convert JPG to WebP from simple desktop apps like Any2Pic, to command-line tools, and online converters.

Method 1: Desktop JPG to WebP Converter (Easy for Beginners)

Any2Pic is a powerful image conversion toolkit that supports batch converting JPG to WebP with just a few clicks.

1. Launch Any2Pic on your Mac or Windows PC.
2. Click Add Images or drag your JPG files into the program window.
3. In the output format dropdown, choose WebP.
4. Adjust image quality or resize options if needed.
5. Click Convert to start the process.
6. The converted WebP images will be saved to your chosen folder.

Any2Pic is fast, secure, and works offline. You can convert hundreds of images at once without losing transparency or metadata.

Method 2: Command Line Tool (Free but Complicated)

For advanced users, macOS supports command-line conversion using cwebp. It is a command-line image conversion tool developed by Google as part of the official WebP library. It’s specifically designed to encode images into the WebP format, which offers smaller file sizes compared to JPG or PNG while maintaining comparable visual quality.

The tool uses both lossy and lossless compression algorithms. With cwebp, you can adjust parameters like quality (-q), compression mode (-lossless), metadata preservation, and even resizing — making it ideal for developers, web designers, and automation scripts.

brew install webp

cwebp input.jpg -q 80 -o output.webp

You can adjust the -q value from 0–100 for quality.

Method 3: Online JPG to WebP Converter (Free but Risky)

If you don't want to install software, you can use online tools such as Convertio.co or CloudConvert.com.

These are web-based tools that let you convert images from one format to another — such as JPG to WebP, PNG to JPG, HEIC to PNG, and more — directly through your web browser, without installing any software. They run entirely on remote servers: you upload your image, the server performs the conversion, and you then download the converted file. They’re designed for convenience, quick access, and cross-platform compatibility.

1. Open one of the websites above.
2. Upload your JPG file(s).
3. Choose WebP as the output format.
4. Click Convert and download the resulting WebP image.

Tip: Online converters are quick for small files but not be ideal for large batches or sensitive images.

Preview on macOS doesn't support exporting JPG to WebP directly. For converting a large number of images efficiently, here is a recommended free tool you can use. Such as ImageOptim. ImageOptim is a free app that supports converting JPG to WebP, reducing file size without quality loss.

How to convert JPG to WebP:

1. Download and install ImageOptim.
2. Drag and drop your JPG images into the app.
3. It will automatically convert and optimize them as WebP, if configured.

Note: You may need to enable WebP support in the preferences or use the CLI tool.

I would recommend the free XnConvert on the App Store. I use it daily.

How to convert JPG to WebP? You can use Online-Convert on your Mac, but I need to give you some important caveats, especially since you mentioned having "a lot of images to get through."

Pros:

• Works in any Mac browser (Safari, Chrome, Firefox)
• No software to install
• Simple drag-and-drop interface
• Offers quality/size customization

Step-by-Step Guide for Online-Convert

1. Access the Website

2. Upload Your Image

3. Adjust Conversion Settings (Optional)

4. Start Conversion

5. Download Your WebP File

My suggestion is not to use the online JPG to WebP converter if it is in large amount or the images are sensitive.

When you upload your photos to a web converter, your images are temporarily stored on a remote server. You have no control over how long they’re kept or who might access them — a serious concern if your images contain personal or business-related data.

In addition, most online jpg to webp converters have upload limits (e.g., 5–100 MB) and can be painfully slow for large or multiple images. If you’re dealing with dozens or hundreds of JPG files, conversion can take forever.

For what it's worth, Any2Pic is not free and ImageOptim does not export WebP files.