First, I meant to order the 1" curling iron so I'm going to give you the approximate circumference of the 3/4" one which is 2 7/8".  When I hold the measuring tape up next to the barrel it measures 3/4".  My hairdresser cut my layers a tad too short last time so my mistake worked in my favor. I'd be burning myself quite often if I was using the 1" size.