In an attempt to clarify this and enable customers to make an informed decision, some years ago the International Organisation for Standardisation (the people who create and control the ISO… quality standards) created a complex page yield testing method – known as ISO/IEC 24711. Much of the technical detail is shown on HP’s website here: but in simple terms page yields are quoted on the basis of a certain amount of ink/toner hitting the page.
When you print emails, letters and the like, on a typical A4 sheet you might cover about 5% of the paper with ink or toner – so 95% of what you see is still plain white paper. If a black cartridge is quoted as – say – “450 x A4 page yield based on 5% coverage” and all you ever printed were typical emails and letters, you could fully expect to get araound 450 pages before the cartridge needed replacing.
But as usual, it’s not quite that straightforward… There are variables like whether you use bold print, or draft quality. Even the design of the font you use can make a big difference. If you choose Ariel as opposed to Times New Roman for example, page yields will change.
The very big change comes when you start printing photographs, maps and pictures. Compared to the typical 5% coverage value above, when you print a photograph you are covering 100% of the paper with ink or toner. Printers obviously mix colours and the use of any particular colour will vary depending on what’s being printed. Holiday snaps on the beach will use a good deal of blue (cyan) and yellow (sea, sand and sky) but rather less red (magenta). Quoted page yields therefore rather go out of the window!
In the unlikely event you wanted to print a number of white A4 sheets completely black – covering 100% as in a photo – the “450 page” cartridge above would actually only deliver around 23 pages!
So remember – page yields are a general guide ONLY – different types of printing will make actual page yields vary enormously. www.inksave.co.uk always try and make quoted page yields clear where the manufacturer provides the information.