The results we give for cost-of-use tests are only an indirect reflection of reality. Since the actual cost of operating a printer is impossible to determine exactly due to the many possible ways that it can be used, we've opted for a relatively simple procedure that tests each printer under the same conditions, and gives a good indication of relative cost of use to use as a basis for comparing models.
- Life span of the black cartridge alone, printing 25%-coverage black documents
- Life span of the color and photo cartridges, printing an A4 document containing 25% black, 25% cyan, 25% magenta, and 25% yellow
Cost calculations were then made using prices from a representative e-commerce site, using cartridges from the manufacturer (never third-party compatible cartridges.) Note that we haven't included the cost of the printing heads, since manufacturers have very different policies in that area. For example, the printing heads are built into HP's cartridges, whereas with Canon they're a separate consumable whose life depends on frequency of use. As for Epson, it would simply be impossible to replace the heads, and the manufacturer claims that the life span of the heads is longer than that of the machine itself anyway. Finally, it was also impossible to determine how much ink is used in the self-cleaning process, since it varies considerably depending on frequency of use; but on the other hand it should make no significant difference in the comparison.
We didn't run any specific tests on the fax function, since only three models out of eight have it - the Dell AIO 962, Canon Pixma MP780, and HP Photosmart 2710. We simply sent and received faxes to see that the function worked well, which it did. The quality is generally better than that of an entry-level fax machine.