Calculating the cost per page for inkjet printers: the ISO standard

The majority of manufacturers have recently adopted a standard for measuring the lifespan of their printer cartridges: the ISO/IEC 24711 test.  And it's very reliable.

In the past, manufacturers used lifespans calculated using the '5%' method, ostensibly based on the fact that printing the 'average' document involves covering 5% of the total surface of the page.  There was no fair way of comparing tests from different manufacturers and the results were rarely trustworthy.  Now though, they use a new standard with very precise parameters, and the specifications of different manufacturers can be compared.



How it works

• The five pages above are printed again and again in standard mode without any settings that would prolong the life of the cartridge, until it runs out.

• This test is repeated at least three times for each type of cartridge to make it more accurate.

What we're most impressed with is the diversity of the pages that are printed.  They're a very good representation of what we print ourselves--and might even involve more colour than most average users produce; they really don't scrimp on ink.  That means we could even say that the lifespan figures that this new standard test produces are lower than you might achieve in reality.  Apart from one detail, that is.

One small problem

The problem?  That the pages are printed continuously.  Nobody ever prints 800 pages in a row.  Instead, after producing half a dozen or so pages, we turn the printer off.  Then, when it's switched on again, the printer often starts an internal cleaning cycle to make sure its nozzles are clean, which wastes some ink.  It might not sound much, but our tests have shown that between 5% and 20% of ink is lost during these operations.  The less you print, the more the printer is switched off and the more ink you waste.

In the past, one of the main advantages of printers with separate cartridges was that they wasted less ink than mono-block cartridges with built-in print heads.  That's no longer the case, as all the manufactures now have print heads in the printer itself, separate from the cartridges.  That makes the consumables cheaper to produce and easier to recycle.

At the end of the day, these factors might well cancel each other out.  On the one hand, the ISO standard uses page that require more ink than normal, but the test procedure itself minimises the amount of ink wasted cleaning.  The results are very useful figures that make an excellent base for comparing printers. 

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