Folks on amazon say that 12" is too big – either the edges don’t cook while the center burns or else the edges of the pot melt the plastic of the cooktop.
Someone said they’d recommend it no larger than 11 1/2" and someone else said the marked circle is 8 1/4".
I have two of this. placed one next to the stove range and one in the back yard. One of them I bought it used at similar price to this. So this is a great deal.
Unlike in the video, I use power level 10 for boiling water.
Temperature mode does not boil water as fast, I believer, the cooktop does not want to overheat it, so it heats slower under temperature mode.