I'm sure it's been discussed before but I am not going to aimlessly wonder through over 1000 pages

I have 22 chicks coming in a few weeks.
I brought out my EcoGlow that I've had for 4 years now, cleaned it, and went to move it to the lower level, and I BROKE IT. Perfect..
So, I am thinking I'll do the heating pad method for the new littles (in my basement).
I will obviously need the bigger heating pad that has been discussed (12x24 i believe?) but will I need two? Or will 1 suffice for my chickies?