With these HP XL cartridges you'll really never have to buy additional cartridges for the rest of your printer's lifetime unless you print quite a lot a regular basis. Me under 10 pgs a month and with my new HP printer that's been with me for a week I may not even run out of ink from the cartridges HP supplied me with in that box but if I do run out I'm secure in the knowledge that when I replace it with the XL I'm set for a really really long time.