Comment 5 for bug 168164

i was having the same problem, posted it on a dublicate bug thread (https://bugs.launchpad.net/inkscape/+bug/168344) and received a useful response that I'd like to share with you all:

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prkos wrote (https://bugs.launchpad.net/inkscape/+bug/168344/comments/9)
Since Inkscape's default DPI is 90 (Inkscape's pixel is 1/90 of an inch), and the usual dpi is 72 you need a little math to get pt right.
If you need 10pt type, use 12.5 in Inkscape, so to get pt you want, use the points number, multiply with 1.25 and you get the Inkscape size.

This is equivalent to the post above that mentions editing svg source. If you don't want to calculate anything and use pt, select your text, go to Edit > XML editor (you'll get svg source for your text object), under Style attribute find where font-size is declared and change the number and unit to number and pt as the unit (for example from 10px to 10pt) and now hit Set button. As soon as you hit Set button you will see your entry in pt changed to the equivalent in px. You're done!