Hmm. Looks like we might need to get down to brass tacks on this one! :P

From what I gather from wikipedia, the point is ≈1/72nd of an inch. Furthermore,

```
"the height of an em-square, an invisible box which is typically
a bit larger than the distance from the tallest ascender to the
lowest descender, is scaled to equal the specified size."
```

Wikipedia goes on to say that in "Helvetica at 12 point, the em square" is "12 points or 1⁄6 in (0.17 in/4.3 mm)". So the em-squares of printed fonts should be roughly as follows:

```
Point Size | Em-square
-----------------------------
12 | 0.17" or 4.3mm
14 | 0.19" or 4.9mm
16 | 0.22" or 5.6mm
```

But there's more to the story. Here's a typographer to share more:
http://www.thomasphinney.com/2011/03/point-size/

Anyhow, if someone would like to take out a ruler (One with metric markings might be easier to use) and try to measure stuff printed using 12, 14, and 16pt fonts, that might be a good place to start. Just make sure that everything is being printed at 100% and isn't being scaled or otherwise modified anywhere along the way.

What OS and what version of LibreOffice are you using?