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Page Coverage Vs. Toner Yield: How They Differ And Why They Don’t Correspond

1 Oct, 2001 By: Buyers Laboratory, Inc. imageSource

Page Coverage Vs. Toner Yield: How They Differ And Why They Don’t Correspond

page coverage has recently become easier for end users with the introduction of
two new software programs that measure the page coverage of documents printed in
networked. By measuring page coverage, these programs are designed to estimate
toner consumption; however, there is a distinct difference between the amount of
page coverage (the percentage of the area of a page that is covered with toner)
and the amount of toner that is deposited on the page, the latter of which
directly corresponds to toner yield, or the number of pages produced by a toner
cartridge. While these two values may appear to be similar, they are two
separate measurements that cannot be extrapolated from each other. In other
words, the amount of toner used cannot be estimated by the amount of page


office equipment dealers may be more concerned with page coverage, on which
cost-per-page contracts are based, end users should be more concerned with how
much toner they’re using on their prints and/or copies. Let’s take a look at
page coverage and how it relates to toner yield, which, for end users, becomes a
vital factor in calculating cost-per-page and ultimately how much a business
spends on printing and/or copying.



we mentioned above, dealers base cost-per-page contracts on page coverage, which
the industry generally sets at averages of 5 percent for printing and 6 percent
for copying. However, with the age of the Internet upon us, industry experts are
saying that these numbers have increased, especially the coverage of printed
pages; some estimates place the average printed page coverage at between 15 and
25 percent. The increase has been attributed to Internet prints, which are
covered with many halftones and graphics, in addition to text.


concept of estimating, or even calculating page coverage, is relatively simple.
Essentially, it’s a measurement of the amount of space on a page that has been
covered with toner. For example, the area of an 8-1/2” x 11” original equals
93.5 square inches; therefore, 5 percent page coverage would equal 4.675 square


actually measuring page coverage is not as simple as the concept may sound since
a page rarely consists of solid areas that would be easy to measure, but more
often consists primarily of text. However, according to Terry Wirth, Director of
Technical Services for Industry Analysts, Inc., it isn’t difficult for someone
to estimate the coverage of a printed page when compared to another original
with a known amount of page coverage. By looking at an original with 6 percent
page coverage—for instance, the Buyers Laboratory Inc. (BLI) Toner Yield Test
Original—an end user can compare it to his or her “average” printed page
and determine the page coverage relatively well. Originals like the BLI Toner
Yield Test Original have been measured with an instrument used specifically for
calculating page coverage, such as a spectrophotometer.



toner consumption can be tricky, to say the least. Unfortunately, the technology
has not yet been developed to monitor actual toner usage as the toner is applied
to the printed page—or the copied page, for that matter. Therefore,
manufacturers, dealers and end users attempting to determine their actual costs
can only estimate toner consumption by measuring toner yield, which is
accomplished simply by producing a total number of pages from one or more toner
cartridges at a constant page coverage (often a true toner yield test may only
be accomplished by the manufacturer or a controlled test lab, such as BLI or
Industry Analysts).


calculates toner yield by printing or copying the BLI Toner Yield Test Original
with 6 percent page coverage until a toner cartridge has been exhausted (BLI
tests toner yield in print mode if available, for instance, on multifunctional
units). By calculating toner yield at a constant page coverage, end users can
better estimate how much toner they will use and how much it will cost for a
specified period of time, which is the ultimate goal of calculating toner yield.


BLI test reports, results of the toner yield test are then factored into a
cost-per-page analysis, which also includes a depreciated purchase price for the
unit and any accessories tested with it, the cost of developer, and an estimated
cost for paper. On their own, the toner yield test results only offer readers a
good estimate of impressions (prints or copies) they may produce at a constant
page coverage with each toner cartridge. Factored into the cost analysis,
however, the toner yield test results offer readers an estimated total cost of
ownership depending upon how many pages they print and/or copy each month.


the example above, an end user can estimate that at an average of 6 percent page
coverage, a toner cartridge will produce about 21,000 prints. And because the
toner yield for all units is tested using the same 6 percent original, an end
user can compare the toner yield of that unit against the toner yield of another
unit covered by a BLI test report. However, while the tested toner yields of
different devices can be compared against each other when tested at a constant
page coverage in a controlled environment, toner yield at other amounts of page
coverage cannot be calculated using these numbers, as we will outline below.


Page Coverage Doesn’t Equal Toner Yield

we already stated, page coverage does not equal toner yield, nor can toner yield
be extrapolated from page coverage. For example, using the example above, you
cannot assume that if the page coverage is doubled from 6 percent to 12 percent,
that half the number of pages—10,500—will be output. The reason is that
calculating toner usage based on page coverage is not a linear function.


the process of producing a printed or copied page, the amount of toner deposited
will vary greatly. According to Industry Analysts’ Wirth, there are a number
of reasons for this, primarily the four listed below:

  • Manufacturing

  • Setup
    of machine

  • Maintenance
    of machine

  • Temperature
    and humidity

last factor listed above may be the biggest variable in the equation. Because
the temperature and/or humidity can affect internal components, which transfer
and apply the toner to the page, the amount of toner actually consumed will vary
according to the unit’s environment. An end user in Florida, for example, will
not get the same toner yield as an end user in Alaska.


critical factor is manufacturing tolerances, which vary from machine to machine.
Depending upon how a manufacturer designs and constructs a unit to operate,
toner usage will vary. For example, BLI recently performed toner yield tests on
two different models that were actually the same machine manufactured by the
same company. While these two units were nearly identical, their toner yield
test results varied greatly. Both units performed well, although the OEM’s
version produced darker, or denser, output; the negative flipside of this
benefit, however, was that the unit consumed nearly twice the amount of toner as
the vendor’s version of the unit, a definite disadvantage in terms of total
cost of ownership for the end user who purchases the OEM’s machine.


is another factor. All units have default settings for density; however, BLI has
found that a vendor may use a default density setting of “5” on a scale of
“1” to “10,” but may publish a toner yield based on a lower density
setting to achieve a higher yield. In addition, an end user in a large office
could change the default setting to get a darker print or copy without anyone
else in the office having knowledge of this fact.


factor that affects toner yield is maintenance of the machine. A machine that is
not well-maintained may consume more toner simply because the internal
components may not operate at their highest efficiency level. As parts grow
older, the unit will consume more toner and thereby yield fewer prints and/or
copies, much the same way a 10-year-old car might guzzle more fuel and/or oil as
its engine ages and degrades due to routine wear and tear.


these factors into account, it is easy to understand why page coverage doesn’t
equal toner yield. If it were merely a question of measuring the coverage of a
specific area on a page, calculating toner consumption would be easy with the
recent availability of page coverage programs. Machines do not use toner at a
constant rate according to the area covered on the page; however, and therefore
toner yield cannot be extrapolated from the amount of page coverage.


illustrate this point, Industry Analysts conducted toner yield tests on a wide
range of units at 5 percent and 6.2 percent page coverage, exhausting two toner
cartridges for each original with both results not varying more than 5 percent
from each other (if the results differed by more than 5 percent, additional
toner yield testing was conducted). While increasing page coverage from 5
percent to 6.2 percent is an increase of 24 percent in actual page coverage, and
one might assume that toner yield should decrease by 24 percent as a result,
this was not the case. The unit with the least variation was the Hewlett Packard
Mopier 320. At 5 percent coverage, the HP Mopier 320 produced 19,979 pages, and
when the coverage was increased to 6.2 percent, the unit still produced 18,877
pages, losing only 5.5 percent of its original toner yield when the page
coverage was increased 24 percent. The unit with the largest margin of
difference was the Xerox Document Centre 265, producing 30,501 pages at 5
percent coverage and only 21,376 at 6.2 percent coverage, losing 30 percent of
its original toner yield. As illustrated by the toner yield tests of these two
units, when increasing page coverage by 24 percent, one lost only 5.5 percent of
its toner yield and the other lost 30 percent.


Toner Yield Into Cost-Per-Page

mentioned above, cost-per-page is important to dealers and end users in
different ways. While dealers are concerned with an average page coverage on
which to base a cost-per-page contract, end users should be more concerned with
toner yield and how much usage they’re going to receive from a toner
cartridge, not their average page coverage.


an accurate cost-per-page can be accomplished only by factoring in the following
values, which are included in BLI test reports:

  1. Cost
    of the unit and/or accessories (total cost of the unit divided by 60 months
    and the number of pages copied and/or printed each month)

  2. Cost
    of service (an average service price is estimated per page)

  3. Cost
    of paper (total cost of cartons required for one year based on number of
    pages copied and/or printed each month)

  4. Cost
    of consumables (cost-per-page for both toner, based on a tested yield, and
    developer, based on the manufacturer’s rated yield)

you can see in the list above, toner is just one factor in the cost-per-page
equation. Page coverage, while it certainly has an effect on cost-per-page,
cannot be translated directly into a cost.



simplest way for buyers to deal with the page coverage/toner yield issue is to
not deal with it at all. By negotiating a cost-per-page contract, under which a
pre-determined cost is applied for each printed and/or copied page, the end user
does not have to worry about page coverage or toner yield. Although most dealers
would rather steer clear of cost-per-page contracts, they are, in the end, the
best possible solution for end users, according to Jeff Smith, BLI’s director
of consumer services. As witnessed by The Buyers Alliance, a division of BLI
that assists customers through the contract process, end users can protect
themselves through cost-per-page contracts that clearly delineate the cost of
each page, including toner, and not have to worry about these issues at all. End
users not interested in negotiating a cost-per-page contract should simply keep
track of the total number of pages printed and/or copied for a given toner
cartridge to determine an accurate toner yield.


the dealer and manufacturer, however, the page coverage and toner yield subject
is just beginning to build steam. Companies are currently developing other
methods to measure page coverage and more programs, both standalone and
embedded, are sure to be on the way in the near future.


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