A modern crematorium takes 1 to 2.5 hours to cremate a body, and the oven gets up to 1400-1600 degrees Fahrenheit.
A wood-fired brick oven can only get up to about 800-1000 degrees Fahrenheit, and that's what they had at Auschwitz.
Firing Your Oven by Chicago Brick Oven- Authentic Wood-Fired Ovens
cremation-oven-room-at-auschwitz - Holocaust Concentration Camps Pictures - The Holocaust - HISTORY.com
So I figure it would take about 4 hours to burn a body to ash, using the Nazi oven method.
Wikipedia says a lot of bodies were burned in open pits, which seems really inefficient and would take forever, so this is hard to quantify:
https://en.wikipedia.org/wiki/Extermination_camp
According to this book (also referenced by Wikipedia) there were 1,471,595 deaths at Auschwitz:
https://en.wikipedia.org/wiki/Auschw...EREFPiper1994b
4 * 1,471,595 = 5,886,38 Jew-Burn-Hours
Divide by 24, and that's 245,265 Jew-Burn-Days
According to PBS, there were 46 ovens at Auschwitz (greatly over estimated numbers, but whatever).
So 245,265 divided by 46 = 5,331 days = 14 years and 7 months.
If all 46 ovens were running 24/7 at full capacity, it would have taken 14 years and 7 months to burn all those bodies. Except the entire 3rd Reich only lasted 12 years. The math just doesn't add up.
Also if you figure in the logistics of getting so many bodies out of "gas chambers" and dragging them one floor down, where the ovens were located and the whole thing sounds surreal.