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Easy batch conversion of files in macOS Finder. Conversion from jpg and png to webp and avif.

macOS App - Quick Webp Avif Image Converter

macOS App - Quick Webp Avif Image Converter

The application converts jpg and png images via the Finder of macOS into the formats webp or avif. The conversion is accessed by right-clicking on one or more marked image files. Quick actions can then be used to create the marked files in webp format, for example.

The file name remains the same, only the extension is changed. Webp images are converted in fractions of a second. With avif, the conversion takes several seconds.

The app can only be downloaded from the Mac App Store. The first 10 conversions are free. That’s enough to try it out. In Germany, the app costs €5.99.

Comparison of file sizes of jpg, png, webp and avif

Images that fit thematically with my blog posts are important to me. Searching for them, creating them or editing them is a lot of work. So far I have only used jpg or png images. I optimised the images with a programme that specialises in these formats. This worked well for most of the pictures. Since I want the images to look good on retina displays, I save them in double width and height. So far, I have output the jpg and png files with 100% quality. That was quite excessive. The result was very large files.

Driven by the comparison of the file sizes, I also reduced the jpg and png files to 80% quality. With very good results. More about this in the PDF table below. Subjectively, I can’t see any difference in quality.

The file sizes surprised me after the conversion with the app “Quick Webp Avif Converter”. As an example, I compared the desktop header image of each blog post with the webp and avif images.

Since I reduced the jpg and png quality to 80% only afterwards, the file sizes of the webp and avif files refer to 100% quality of the jpg and png files. However, this allows for a realistic comparison. The results are summarised in the following PDF:

Some explanations on the comparison of the image formats in the PDF table

The header image of “broken-links ” was already blurred in the lower image area in the original. Since I couldn’t find a better picture at the time, I used it anyway.

pagebundle-img ” and “shorten-links ” are smaller in jpg format than the webp variant. However, all browsers use the webp format.

For the PNG images “header-links ”, “front-matter-slug ” and “canonical ” I apparently used 80% quality at the time. So no reduction.

The image formats jpg and png

By reducing to 80% quality with another programme, the file sizes could be significantly reduced. Subjectively, no difference to 100% quality is noticeable.

The image format webp

Webp is the clear winner at 80% quality. Subjectively, I cannot see any difference between the jpg and png images with 100% quality and the webp images with 80% quality. On my website, only very few png images are used as header images. Therefore, the direct comparison is only meaningful with jpg images:

  • jpg images with 100% quality versus webp images with 80% quality.
    The savings range from 4% to 92%.
  • jpg images with 80% quality versus webp images with 80% quality.
    In this comparison, the savings range from 3% to 48%. For three images, the jpg files are between 8% and 11% smaller.

Why this wide spread comes about is not known to me. But overall, the webp images are smaller.

What surprised me was that when I generate the webp files with 100% quality, they are in most cases larger to twice as large as the jpg images with 100% quality. With the png images, the picture is inconsistent.

The avif image format

The file sizes of avif have disappointed me. At 80% quality, most of the images are only slightly smaller than the jpg images at 100% quality. At 100% quality it looks even worse. It will probably take a few more years for the format to produce significantly smaller file sizes.


The application’s functions, which are integrated into the Finder, are easy and intuitive to use. The creation of webp files from jpg or png is very fast. The same process with avif files takes several seconds on a MacBook Pro with M2 Pro and 32 GB Ram. The file size of avif files is disappointing. The file size of well-optimised jpg files with 100% quality is only just reached by avif in most cases, even with 80% quality.

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