I've personally never used hard wax but I did hear that it's pretty great on more sensitive areas. I've been dying to wax my bikini area. Anyway, I've been reading and all I could find was this blog here: http://www.epilatorhome.com/best-hard-wax-hair-removal-products-know/
the girl reviews different brands including GiGi Hard Wax, might be useful.
What she says is that GiGi's volume is 14 ounces, might be a good idea to check your warmer's volume but I think 14 is a regular size.
She also says that GiGi isn't really good on large body parts since it's not really efficient, so do consider. She instead recommends to use Necessities Azulene hard wax if you're aiming at legs, tummy, arms, etc. I hope this helps at least a little bit