Helping people with computers... one answer at a time.
When a PDF is printed, even though it may be standard sized pages, the printer may add margins. You can adjust this behavior when you print.
Why do my PDF's print out smaller than the original copy?
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I'm going to assume you mean slightly smaller, since that's a very, very common scenario. I see it myself all the time.
The answer, in a word, is margins. And depending on the PDF document and the capabilities of your printer, you may, or may not, be able to work around it.
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Most PDF documents are intended to be a representation of an equivalent paper document. That means that they're typically sized as if they were paper. That means they usually represent a paper size 8.5 by 11 inches (or perhaps A4 sized paper in Europe).

When you view the document in a PDF reader, it provides a view on those series of pages, but they're still conceptually pages.
Now, when you print your document, it would seem logical that an 8-1/2 x 11 page would print just fine on an 8-1/2 x 11 piece of paper. Sadly, that's typically not the case.
The problem is that most printers cannot actually print on the entire sheet of paper. There's a "margin" around the outer edge that will vary depending on the printer. It's usually around 1/4 inch (but I must emphasize that this varies greatly depending on the printer). The upshot is that a printer will only be able to print on an area somewhat smaller than the full 8-1/2 x 11.

Now, when printing there are two choices:
You can print your 8-1/2 x 11 document directly on to the 8-1/2 x 11 paper, and risk cutting off from view the edges of whatever is presented in the PDF.
You can resize the 8-1/2 x 11 document down to a size that will actually fit entirely in the printable area of the paper.
The later is the most common default, and it's likely exactly what you're seeing.

Before and after - ever so slightly smaller to fit in printable
area.
The thing to look for in your PDF viewer is "Zoom" or "Page Scaling":

As you can see the default is "Fit to Printable Area", exactly as I've described. (And you can see a "Zoom" of 97% has been applied just under the preview.)
Now, the example page I'm using would actually print just fine without being resized smaller (since it actually has margins of its own).
Simply change the "Fit to Printable Area" to "None", you'll see the "Zoom" disappear or reset to 100%, and the PDF reader will attempt no scaling - it'll just print the 8 1/2 x 11 document onto 8 1/2 x 11 paper. If there's clipping because of the printer margins, so be it.
Article C3604 - December 28, 2008
I am sending a .pdf document by email for a company to print. They just called and told me the first two letters in each row are cut. Since I have no access to their printers, how can I change my document from my end?
Thanks!
13-Jan-2009
Thanks for the article. Unfortunately, even with the page scaling set to "none" I'm still having documents print out smaller than the originals (converted from Word 2000 with PrimoPDF). I know that my printer can handle the necessary area (I can print the document from Word with no problems at all) so I'm totally baffled as to why printing the pdf version causes it to shrink.
It's really very odd.
Posted by: Bert Coules at November 12, 2009 12:59 PMVery good to understand. My problem: how can I print without margins from a batch-job (DOS-Box) ? There is no option for "not scaling" ...
Posted by: Joerg at December 7, 2009 12:34 AMMy problem is similar to one above (Bert Coules, Nov 2009). I can print PDF without scaling down (Page scaling: None), but my page nbr and other folio material are cut off at page bottom. Again, I know it is not the printer because the PDF creator (InDesign) prints fine. Why the difference? Seems Acrobat introduces a fatter NO-PRINT zone at page bottom . . . and we need prints at 100%, so again, scaling will not work. Help.
Posted by: Joe at August 12, 2010 12:16 PMWe create forms as PDF's that we publish on our WEB site. We also have vendors that produce the same documents with 2D barcodes as PDF's. We scan/image the returned doucuments and run OCR, ICR and 2D interpretation of data. When the public prints the documents in Adobe Reader with scaling set to none (or actual size in Reader X), everything is fine. The issue is when the the users leave the size option set to something other than none or actual. We have margins over 1/2 inch on all sides and the pages will always scale. This moves the exact positioning of the fixed print documents and shrinks the 2D barcodes to where they are unreadable. We have the page scaling set to none in the document itself but of course the user can always override.
I have been told that if you change the size of the page to something less than 8 1/2 by 11, you can prevent the scaling. I have played with this and found that what works best for a laser printer is different than what works with an inkjet. Does anyone know a size that will prevent scaling on the most printers?
Posted by: nebigfoot at January 27, 2012 5:30 AMIs there any other way to prevent a PDF document from scaling? I have even created a PDF with one word in the middle of am 8 1/2 by 11 page and it will still scale.