The conversion factor between electron charge (e) and coulombs (C) can be calculated using the charge on an electron.
1 electron charge = 1.60 x 10^-19 C
So, the conversion factor can be written as:
1 e = 1.60 x 10^-19 C
This means that 1 electron charge is equal to 1.60 x 10^-19 coulombs.