Printing, effective print width?

[Folmer]

At the moment I am working on a series of templates. To ensure all text has the same size when printed, the same font and size is used (Arial 10, set as normal font) and printing is done at 100% scaling. Additionally the paper needs to be filled right up to the margins. For this I would like to know the effective printing area, so the columns can be scaled to fully utilise the paper width.

For a landscape A3 the paper width is 42 cm. When the margins are set at 1 cm on all sides you would expect the effective width to be 40 cm,.... but it isn't.
In page break view I changed the column widths until all columns just fit on 1 page. Using Selection.Width / Application.CentimetersToPoints(1) the total width in cm was returned, which showed 37.99 cm. I then proceeded to see if I could find where the difference comes from, and this is where it get interesting (read: confusing and frustrating)
- Changing the normal font to Arial narrow --> available width showed 39.45 cm
- Changing the print DPI from the standard 600 DPI to 72 DPI --> available width showed 34.82 cm
- The number of columns used also has a very small impact, albeit a few millimetres.

Does anyone know how the usable print width is determined? Of course it is possible to program all setting to the required standard, but I like to know how the useable print width is determined so I don't miss any settings and can anticipate for other page sizes.

Thanks.

[Roel Jongman]

My guess would be it has got to do with the fact that Arial is a proportional font (most fonts are) which means that every character have their own width.
I think to avoid that excel cannot print all characters in assigned space they "reserve" the max needed space for a character making the available width less.

Arial Narrow probably has a smaller variation between smallest width and largest width needed for a character.
you cloud try the theory with a mono-spaced font like courier new (looks ugly, i know, it's just to test the theory)

This is an example text (arial)
This is an example text (arial narrow)
this is an example text (courier new)

[Folmer]

As you expected, this shows a nice (or at least close enough) 40 cm width. But as you said it looks ugly and is not according corporate standard.
Still leaves the problem of how to predict the size when using a proportional font...?

[Folmer]

Ok, this just got annoyingly weirder.

I thought I had fixed it, but then a colleague open the sheet on her computer and the available print area was different again. Even when using the same printer...

Please, can someone shed a light on this as I really would like to fix it in a way other than "scale to fit".