How are the credits counted when using Autoptimize?

Autoptimize has an image optimization feature provided by ShortPixel that processes and serves images on the fly via a fast CDN with a global presence. Unlike ShortPixel Image Optimizer, Autoptimize does not optimize the physical files on your server.

Autoptimize only optimizes your images if they are viewed at least once from your front-end. Until that happens, the image will remain un-optimized. Here's more information about how Autoptimize's image optimization works: How does Autoptimize and its Image Optimization + CDN service work?.

Once the image is optimized, it is stored on the ShortPixel CDN servers and it can be served to your clients using the CDN traffic quota you purchased from ShortPixel. As long as there is enough CDN traffic quota available, your optimized images will be served from our CDN.

Note: One-time credits, the legacy monthly plans and Unlimited plans can be used to process images.

How much CDN traffic equals a credit?

  • 1 credit = 5 MB of CDN traffic
  • Free plan = 100 credits = 500 MB of CDN traffic = ~500 visits/month
  • $4.99/month plan = 7,000 credits/month = 35 GB of CDN traffic = ~35,000 visits/month
  • $9.99/month plan = 16,000 credits/month = 80 GB of CDN traffic = ~80,000 visits/month
  • $29.99/month plan = 55,000 credits/month = 275 GB of CDN traffic = ~275,000 visits/month
  • $49.99/month plan = 100,000 credits/month = 500 GB of CDN traffic = ~500,000 visits/month
  • $99.99/month plan = 220,000 credits/month = 1.1 TB of CDN traffic = ~1,100,000 visits/month

If you purchase the Unlimited plan, you do not have to worry about how many credits you spend. The Unlimited plan just has a 500 GB CDN quota. If you exceed this limit, you will have to wait until the next month for the quota to be replenished, or you can buy one-time credits and use them according to the figures below.


Say you own a small website with about 100 pictures distributed between your pages, and it is visited monthly by 300 visitors.

The 300 visitors will most likely generate less than 300 MB of CDN traffic per month, and they won't exceed the free monthly CDN traffic, which is 500 MB.

If tomorrow your website goes from having 100 pictures to 300, and you keep having the same number of visitors, you will use, on average, 900 MB of CDN traffic per month, and you will probably have to upgrade to the Unlimited plan.

What happens if I use my own CDN?

If you choose to use a different CDN than ShortPixel's, then no traffic will be counted. Instead, every 30 days you will use the following:

  • 1 credit per every image size optimized. The optimization happens when at least one visitor sees the image.
  • Another credit if the image is delivered in WebP format.
  • Another credit if the image is delivered in AVIF format.

That means a maximum of 3 credits per image size, every 30 days.

If you are using the Unlimited plan, you will not be restricted by the 500 GB monthly limit of CDN quota.

Here's how you can use a different CDN with Autoptimize: Can I use a different CDN with Autoptimize?