Yes you can. You can measure and/or dimension things to scale in a PDF, including AREA calculations.
You’ll need Adobe Reader XI, Adobe Acrobat Pro or, if you’re like me, Foxit (free PDF viewer). I like Foxit because (1) it’s lightweight and (2) it puts all open documents in tabs. (Get with the times, Adobe.)
Note: earlier versions of Adobe Reader didn’t let you measure unless the author enabled Measuring and Comments.
Before I start, I need to warn you, Adobe did a terrible job with this tool. It’s hard to find, the different components are located in completely different areas, and it’s a bit ugly.
Adobe Reader XI (also applies to most of Acrobat Pro)
In the Edit menu, select Analysis > Measuring Tool. At the upper-right you’ll now see Snap Types and Measurement Types:
You’ll notice you can snap to nearest line, end points, midpoint and intersection. Personally I don’t use the snaps because they’re a little wonky. Then to the right you’ll see three types of measurement: linear distance, perimeter and area. For perimeter and area, you can close the line by getting close to the start point (you’ll see a little O next to your cursor)–double click to close the line.
At the bottom right you’ll see a status of what your scale is and what you’re measuring:
The most useful part of this display is the Angle. For some reason you can’t dimension an angle as a comment on the PDF, but you can see what it is here.
The dimension will appear as in any drafting program. It will also come with its own comment popup, which you can minimize or add comments to, if you like.
At any point you can right-click somewhere on the page and change the scale of your measurement. Make sure you’re still using the Measure Tool (not the black arrow or hand tool). The first option on the pop-up contextual menu will be “Change Scale Ratio.” You can change either number, i.e., 1/4″ scale can be 1 inch = 4 feet or 0.25 inch = 12 inches.
Before setting the scale I recommend finding something to verify your scale. If there’s a graphic scale, measure it at 1:1 scale first and check your numbers. Or if there isn’t a graphic scale (does anyone use those anymore?) find something like a 36″ door to confirm.
Note: sometimes a PDF will have a scale built-in. That’s usually ok, but I find more times than not, the scale is wrong. If you’re having trouble setting the scale, go to Preferences (Ctrl+K) > Measuring (2D) and uncheck “Use Scale and Units from Document (when present).”
Like with any comment/markup in Acrobat, you can change the style with Ctrl+E. A little toolbar will pop up, showing you everything that can be modified. You can also modify dimension properties by right-clicking on the dimension line and choosing “Properties…” (Here, for some reason they give you a dialog box instead of a toolbar.) Right-clicking will also show you options like “Flip Line” and “Add Label.” And to make it just a little more complicated, you can also right-click on the dimension line and select “Measure Preferences” (same thing as Ctrl+K > Measure (2D)).
TIP: In case you didn’t catch that, you can use Ctrl+E with any markup. If you have a text box, Ctrl+E will let you set the font, font size, font color, background/border colors etc.
You can also right-click off a dimension line (anywhere else on the page) to get a different pop-up menu, with things like “Turn Ortho On” (also available in Preferences) and “Export Measurement Markup to Excel” (I haven’t found this useful yet).
I haven’t found a way to override the dimension text. So if you see “4.01 in” and want it to appear as “4 in” you can either fiddle with the start and end points until you get exactly what you want, or you can do what I do: create at text box (comment), type in “4 in”, then drag the text box over the dimension text. If you want to be a little more stylish, you can use Ctrl+E to change the properties of the text box (white background and border, smaller text maybe).
Adobe Acrobat Pro X
Just about everything is the same for Acrobat Pro (Version 10) as it is with Reader XI, except:
The tool is found in the right pane (now that you’re a Pro, you get a button, not a menu item):
Under “Analyze” (Measuring Tool). The thing is, Acrobat hides this by default. To make it appear, go to that little icon of a little menu and select “Analyze” at the bottom.
TIP: Right-click on this “Measuring Tool” button to get “Add to Quick Tools”–the icon will be added to your toolbar at top for easy access.
You can find the measuring tools (Distance, Perimeter, Area) in the Comment menu. There aren’t a lot of formatting options here. What you see is what you get. But it gets the job done.