The HP DeskJet 940C uses two ink cartridges: black HP 15 (C6615DN), which yields about 840 pages, and tri-color HP 78 (C6578AN), which yields about 710 pages. Both are compatible ink, standard capacity. The same supplies also fit the DeskJet 920C, DeskJet 940cvr and DeskJet 3820. Same-day shipping on most orders.
