Cost Per Page (Print And Photo)
The cost per color page is calculated on the basis of a given area of coverage per page and is quite high: 5% per color (5% cyan + 5 % magenta + 5% yellow + 5% black) on an A4 surface (letter-size paper).
The black and white cost represents an area of coverage of 10% black.
The cost of a photo is that of a 4 x 6 in (10 x 15 cm) print. It is calculated by adding the cost of the ink required for the area of coverage given above to the cost of the paper recommended by the manufacturer. In the case of the paper, we took the cost per A4 page, divided by four. This produces A6 prints (105 x 148.5 mm, very similar to the 10 x 15 cm and 4" x 6" formats, but much less expensive).
The paper we used was Plus Glossy PP-101 Photo Paper. It is less expensive than the Pro PR-101 Photo Paper, but almost as good and stronger because it is more scratch-resistant.
Overall, it seems that using the single-block Canon cartridge (i250, i350, i450, i470D) is twice as expensive (in both black and colored ink) than using separate cartridges (i550, i850).
There is less difference in photo mode simply because of the high cost of the paper, which accounts for almost half of the final cost of the prints.