Question: how many ppi is 1 dpi?
Answer: ppi↔dpi 1 ppi = 1 dpi. ppi↔pixel/m 1 ppi = 39.370079 pixel/m. ppi↔pixel/cm 1 pixel/cm = 2.54 ppi. ppi↔pixel/mm 1 pixel/mm = 25.4 ppi.