Hello Nicolae,
I'm Baptiste from the developer team.
As you probably know, we are charging an additional 0,10€ / Gb. To calculate the bandwidth usage, we sum up the following:
- Imgix regular charges.
- The total number of bytes that Prismic sent to you in response to the request, including headers.
- Cost of hosting the images in Prismic.
Please let me know if you have more inquiries.