Crematoriums

Do crematoriums charge by the pound, like butchers do, $1.99 a lb or whatever?.
I’m thinking since my tissues, organs, etc, will be donated when I die, I should get a better rate since I will weigh less.
It would take less gas to do the job.

The ones my family have used have always charged a flat rate per, uh, person.

Charging by the pound (or even charging extra for severly obese subjects) would be a PR nightmare. I do know that extra-large coffins cost more than normal ones and it’s possible for someone to be obese to safely cremate (at least intact).