Grab your tape measurers! The toilet paper roll test.
I would like others to experiment and compare results with me on this.
Take a toilet paper roll, and measure the outside girth (I recorded 5.25” and I measured twice)
Measure the inside girth, make sure the tape is tight to get the largest number possible (I recorded 4.75” and I measured twice)
Now, measure the width of the paper roll, you may need to use MMs to measure (I recorded 1 mm and I measured twice)
And just for the hell of it, measure the diameter of both inside and outside (I recorded approximately 44mm at the largest for the outside and approximately 40mm at the largest for the inside, measuring many times)
Girth in mm according to the formula 3.14 * diamter = (138.16 mm girth for outside and 125.6 mm girth for inside)
Results: An increase of 1 mm around the entire circumference will increase girth by 0.5”
This could be why EQ is so important, because even 1 mm less of compression could increase your “felt girth” by 0.5”. Also, this could be an indicator of how truly difficult it is to obtain girth; you are trying to increase your girth by numbers smaller than millimeters for a noticeable gain.