i couldn't calculate right factor due fact that i don't know how many ink machine uses for printing.
to calculate factor, you have to know how much ink you used in print. I had idea to measure weight of cartridge before and after printing 1 m2 of 100% of some ink, to calculate how much it was used. but this would be ok if there's no secondary tank between cartridge and head. so, it's almost impossible to calculate how much ink seiko really uses for print.
you can always guess, but then it's much accurate and easier if you divide on one year bases how much meters you printed and how many liters of ink you bought...
