# Printing Press ink consumption based on the artwork area coverage.

#### RobL

##### New member
I ran a Test Job on the press, so I have all the data. Artwork Area Coverage / Ink consumption / Cost.

Test Job 1 ...

Artwork Coverage - cm2 = 312371 or I can use inch2 = 48417.7 (this is the area of the artwork that will have ink applied)
Ink Consumption - 0.217044 millilitres (how much ink was used to print the above artwork)
Ink Cost - 1 litre of ink = £ 26.00
0.217044 millilitres x 26 = £ 5.64

Now the question is .... I would like to calculate the cost to print an artwork before it goes to press. I will know Artwork Coverage and Ink cost but not know the Ink Consumption

Taking the test job as an example I will know ...

Artwork Coverage - cm2 = 312371 or I can use inch2 = 48417.7 (this is the area of the artwork that will have ink applied)
Ink Consumption - ??????????
Ink Cost - 1 litre of ink = £ 26.00
?????????? millilitres x 26 = £ ??.??

#### RobL

##### New member
Help please ... I am trying to work out a way to calculate printing costs without knowing the ink consumption before hand. This way we can select the printing device that is the most economical on ink cost.

Example Job that HAS been printed on press ...

Artwork Area
that will receive ink - cm2 = 312371 or we can use inch2 =48417.7
Ink Consumption - 0.217044 millilitres
1 litre of ink = £ 26.00

Calculation = 0.217044 millilitres x 26 = Cost to print job is £ 5.64

Example Job that HAS NOT been printed on press ...

Artwork Area
that will receive ink - cm2 = 312371 or we can use inch2 =48417.7
Ink Consumption - ?.?????? millilitres ( The Question is ... How would I calculate the above area data to reach 0.217044 millilitres )
1 litre of ink = £ 26.00

Calculation = ?.?????? millilitres x 26 = Cost to print job is £ ?.??

( Artwork Area that will receive ink - cm2 = 312371 or we can use inch2 = 48417.7 ... These values will be variable based on the artwork received. )

#### BigBeachBanana

##### Senior Member
Ink Consumption - 0.217044 millilitres
1 litre of ink = £ 26.00
Calculation = 0.217044 millilitres x 26 = Cost to print job is £ 5.64

Your info provided is inconsistent. Is it litre or millilitres?

#### RobL

##### New member
Hi BigBeachBanan, the ink is supplied in 200 litre barrels at £ 5,200 / £ 26.00 a litre. The data I get from the press is in millilitres. So to keep it consistent a barrel is 200000 millilitres at a cost of 0.026 per millilitre. Using the example job ... 0.217044 millilitres x 0.026 = 0.005643144 (£ 5.64)

#### Dr.Peterson

##### Elite Member
I ran a Test Job on the press, so I have all the data. Artwork Area Coverage / Ink consumption / Cost.

Test Job 1 ...

Artwork Coverage - cm2 = 312371 or I can use inch2 = 48417.7 (this is the area of the artwork that will have ink applied)
Ink Consumption - 0.217044 millilitres (how much ink was used to print the above artwork)
Ink Cost - 1 litre of ink = £ 26.00
0.217044 millilitres x 26 = £ 5.64

Now the question is .... I would like to calculate the cost to print an artwork before it goes to press. I will know Artwork Coverage and Ink cost but not know the Ink Consumption

Taking the test job as an example I will know ...

Artwork Coverage - cm2 = 312371 or I can use inch2 = 48417.7 (this is the area of the artwork that will have ink applied)
Ink Consumption - ??????????
Ink Cost - 1 litre of ink = £ 26.00
?????????? millilitres x 26 = £ ??.??
You forgot to change the numbers for the second example, but we don't really need an example.

The ink used should (in principle, at least) be proportional to the area. (I can imagine some other effects, some random, complicating it slightly, so actual numbers could be off a little.)

So calculate the milliliters per cm^2 from your known case, and multiply the area of a new job by that to get ink usage. Then, of course, multiply that by the cost in pounds per milliliter to get the cost.

But in your first example, you multiplied ml by 26 £/l rather than 0.026 £/ml. Which of your numbers or units is wrong?

#### RobL

##### New member
Hi Dr.Peterson, thank you for the reply.

"So calculate the milliliters per cm^2 from your known case, and multiply the area of a new job by that to get ink usage"

The problem here is I will not know the millilitres at the time of calculating the cost. AlI I will know is the cm^2 (Area) and the cost per Millilitres (Volume)

#### Subhotosh Khan

##### Super Moderator
Staff member
Hi Dr.Peterson, thank you for the reply.

"So calculate the milliliters per cm^2 from your known case, and multiply the area of a new job by that to get ink usage"

The problem here is I will not know the millilitres at the time of calculating the cost. AlI I will know is the cm^2 (Area) and the cost per Millilitres (Volume)
You will know the mL/cm2 from your previous job.

Now multiply that number by the area of the new job (cm2). The result will be volume of ink needed for new job (mL).

#### Dr.Peterson

##### Elite Member
Hi Dr.Peterson, thank you for the reply.

"So calculate the milliliters per cm^2 from your known case, and multiply the area of a new job by that to get ink usage"

The problem here is I will not know the millilitres at the time of calculating the cost. AlI I will know is the cm^2 (Area) and the cost per Millilitres (Volume)
Are you saying that it is not true that the ink usage is proportional to area printed? Why is that?

If you know nothing about how ink usage is related to area printed, then what you ask is obviously impossible.

What I said, assuming proportionality, was to calculate the rate of ink usage from the known case, namely 0.217044 ml / 312371 cm^2 = 0.0000007 ml/cm^2 if your numbers and units are correct. Then, if the rate remains the same, you can multiply that by a new area to find the amount of ink needed.

Also, you haven't answered my question about your misuse of units, which was also mentioned in the second thread you (inappropriately) posted while waiting for moderation. It looks like you attempted to answer that question there, but you are still inconsistent.

#### RobL

##### New member
Thank you both ... I have attached a file to hopefully explain myself better.

#### Attachments

• test files run_converted.pdf
1.5 MB · Views: 4

#### BigBeachBanana

##### Senior Member
Ok to keep it simple,
What it cost you per [imath]cm^2[/imath] based on your previous job:
$\frac{£5.64}{312,371\,cm^2}=\frac{£0.000018}{cm^2}$Then let say you have a job for [imath]500,000\,cm^2[/imath], then it would cost you:
$500,000\,cm^2\cdot\frac{£0.000018}{cm^2}=£9.028$So in general,
$\text{Cost of ink for the job}=(\text{Number of}\,cm^2 )*\frac{£0.000018}{cm^2}$

#### Dr.Peterson

##### Elite Member
Thank you both ... I have attached a file to hopefully explain myself better.
This shows one important fact you hadn't mentioned, which may explain the factor of 1000 you've omitted: You're calculating the cost of 1000 copies, not of one.

So your actual price calculation, as I understand it, is 0.217044 ml per copy x 1 liter/1000 ml x 1000 copies x £26 per liter = £5.64 for 1000 copies. At least, that's the best explanation I can think of for your multiplying milliliters by price per liter but getting a presumably correct result.

To put it another way,
Using the example job ... 0.217044 millilitres x 0.026 = 0.005643144 (£ 5.64)
It isn't true that 0.005643144 = £ 5.64.

Your last step here appears to be to multiply 0.005643144 per copy by 1000 to get £ 5.64 for 1000 copies.

#### RobL

##### New member
Good Morning Both and thank you for the above.

The delay in me coming back to you has been due to running these calculations on a volume of work. Unfortunately I am seeing inconsistent results. I trust the math so I'm thinking it's my explanation that is either unclear or just wrong ... or what I am trying to calculate is just impossible.

Not wanting to flog a dead horse but would you mind looking at the attached, I have been as clear as possible, if this doesn't work then I feel I am asking the impossible.

#### Attachments

• area to volume v2.pdf
2 MB · Views: 6

#### Dr.Peterson

##### Elite Member
Good Morning Both and thank you for the above.

The delay in me coming back to you has been due to running these calculations on a volume of work. Unfortunately I am seeing inconsistent results. I trust the math so I'm thinking it's my explanation that is either unclear or just wrong ... or what I am trying to calculate is just impossible.

Not wanting to flog a dead horse but would you mind looking at the attached, I have been as clear as possible, if this doesn't work then I feel I am asking the impossible.
I see nothing here to comment on.

Please tell us what inconsistencies you see! It appears that you are mostly just stating a problem (the second job) without showing what results you calculate for it or how they compare to actual results.

I would expect calculated values not to match exactly with reality, because reality has a way of evading formulas (e.g. because of factors you aren't taking into account).

#### RobL

##### New member
OK ... thank you for taking a look.

#### BigBeachBanana

##### Senior Member
OK ... thank you for taking a look.
The obvious difference is the amount of ink used per [imath]cm^2[/imath]. Without knowing much more, I would guess it's because your printers aren't precise or not calibrated, so it produces a variance in your result.