Hi Caterina, I will try to include centimeters on the projects from now on. I don't know why I don't do it now, the centimeters are on the the same ruler I use for inches.
For the large lamp shade measurements: 3.5 cm long; measuring inside the lines for the width of the top 11 mm; measuring inside the lines for the bottom width 19 mm; the glue line at the top of the shade is 4 to 5 mm down from the top.
I think the most important measurement is that the top of the shade be the same as the sides of the center.
The small shades I make are 2.5 cm tall. Have fun, Kris