Depends on the warmers, but I would shoot for at least a 2000 watt generator (make sure it can do the full 2000 on one plug). Generator is on my list, but not towards the top yet.

 

I'm looking at the Chicken Hawk Racing with digital temperature monitor

 

I use a Honda EU2000 generator, and I run the single temp red chickenhawks.
1 tank of fuel last a whole day, and I never turn it off, just unplug and run the session, come back in and plug them back in.

 

That's cool. I didn't know if the generator would grow off the electronics in the digital dial like it dose on must electronics from my experience (super storm sand days)

 

I use a Elite Series powered by a 10HP Briggs and Stratton. It has 5500 running watts. It's not a big name brand like Yamaha or Honda and it's a little loud, but I got it dirt cheap. I've used it to power three sets of Chicken Hawk warmers.