USEI conductors are jacketed. Single conductor wire used to have a cloth jacket.
On a similar topic, Table 6 is for stranded conductors. Solid conductors are a little smaller but you can always use Table 6. It's the worst-case measurement.
When you need to push it, you can use the manufacturers measurements and when you really need to push it, you can measure the wire and the conduit.
Here are some tables using the manufacturer's specs: http://www.codemath.com/cgi-bin/Run.pl?script=FillTbls