I am looking to put Electric Baseboard heat in a basement, it is approx. 25'w x 30'l. I am looking to put in 3 to 4 six-foot units that are 240v, 1500w & 6.3A. Will this be enough, or too much? What is the calculation for btu's to sq feet? The unit, which I selected, is 5100btu's ea. Is there a way to get a projected cost of usage? Hopefully someone out there can help? "Lost in space - heaters that is."

What you need in the way of heaters and how much power they are going to use is highly dependent on how well sealed and insulated the basement. If you left finishing the walls go until you ran the wires, you can still caulk between the foundation, plate, band joist, and sub floor. Newer houses have a layer of foam between the plate and foundation, but may still need caulk above and below the band joist. Also seal around all the pipes and wires. The space around a drain pipe may provide a direct route for warm, moist air straight to the attic. Leave sealing the same pipes in the attic go for warmer weather. Foam insulation provides a higher R value per inch and is less susceptible to moisture problems than fiberglass. Either needs to be covered with drywall or other flame barrier.

So tighten up first. I would then run heavier wires than you hope you need, 10-2 isn't that much more than 12-2. Then skimp on heating units. If you have heavy enough wire, you can add more later.