It's very inefficient to compress all my site's images in Google's preferred compresion by running webpage after webpage in Google GPI, downloading all images and upload one by one to my CMS image directory.

I would prefer doing so only if no one outside Google know what compression mechanism they use (their compression mechanism is most likely not the one used by tinyPNG).

My question:

What image compressor Google Pagespeed Insights uses?

I ask since I thought just to simplify everything by downloading all images to my PC, compress them that way, and thus saving all stages of the GPI valuable-but-sisyphic process.


  1. If it's only a matter of compression percentages, please note the minimal percentage needed to "satisfy" GPI.

  2. If any manipulation by ImageMagick is the efficient way to go, please remind it in your answer.

Why I believe this is not a duplicate:

Here's why I believe this is not a duplicate and should be untagged as such:

The question "Google Pagespeed: New image compression rules?" that appears as such asking about changing of the algorithm in a specific time and place. It is not the same as "What is the compressor used", not by means of question theme or by means of my aim to bring more people to WM SE from Google searched regarding my specific question. Please remove duplication notification.


1 Answer 1


It's not the specific compressor you need to know here. It's actually the amount of compression that is key.

Uploading images without compression will provide original quality images at a price of a larger download.

If you compress them just enough, then you'll get excellent quality images since people don't scan most images they see on the internet one pixel at a time.

If you compress them too much, then the image will appear degraded and users might complain.

What I would suggest if your images are jpeg is to compress about 20% to 30% so that the quality is about 75%.

If you're trying to please pagespeed insights, I'd experiment with compression, starting at 20% and increasing by say 5% each time until google no longer complains.

  • Do you know how much percent TinyPNG uses?
    – user58733
    Commented May 18, 2017 at 5:21
  • Or maybe, can you check to how much percent GPI compresses?
    – user58733
    Commented May 18, 2017 at 5:50
  • I happen to compress mine with PHP's GD image library If you know PHP programming, you could run hundreds of images through your PHP code and have them all compressed. Commented May 18, 2017 at 6:03