Auschwitz had 4 crematoria
the killing operation lasted for less than 1,200 days
1.2 million were killed and cremated
it takes 2+ hours to cremate a human body
does the math add up?
Discussion
Yes, since most of the victims were barely more than skin and bones, and the executioners routinely fit three bodies into a unit at a time.
Also, they didn't economise on fuel like civil crematoriae do today to get you that 2 hr figure.