Run length


Room layout dictates the sub is on the opposite wall. Not ready to run a wire across the floor. It would be 26 feet.

To skip the floor run I would have to go up and down inside the wall. That would add another 18 feet for a total of 44 feet.  Too long?  Will be using plain old 14AWG cord.
ibmjunkman
If your sub is 4 Ohms, the wire is more of a factor that if it's 8 ohms. You might consider 12 gauge wire. I use 14 gauge solid (twisted) for very long auditorium runs with no problems. There is flat, 50 conductor computer cable on the surplus market (65 cents/ft. in 100 ft. reels) that will be undetectable under a rug. It's ugly, but who needs to see it? Use 25 strands for plus and the rest for -.
Why run a sub at all?? Are your speakers not good with bass? Ditch the speakers and the sub and buy speakers that do bass well.