How do we know the size of the extermination area in the death camp of Sobibor was large enough to contain the mass graves?
Holocaust deniers claim:
The size of the extermination area of the Operation Reinhard death camp of Sobibor is too small to have accommodated the number of bodies of the alleged victims.
The facts are:
Modern forensic and archeological investigations at Sobibor show that there are at least 7 mass graves in the camp, the size and volume of which are more than sufficient to accommodate the number of victims.
Holocaust deniers claim that it is not possible that the Germans could have “buried roughly the equivalent to the stadium spectators of the Rose Bowl game” (about 80,000 people) in the Sobibor death camp in a mass grave only a little larger than “a henhouse.” For example, the self-named “Denierbud,” an American Holocaust denier video maker, claims that Karl Frenzel, an SS guard in Sobibor, was convicted partly based on flimsy evidence about this impossibly tiny grave.
Denierbud makes the same faulty assumptions as he did for the graves in the death camps of Belzec and Treblinka.
Denierbud’s calculations about the size and volume of the mass graves at Sobibor are based on the same faulty assumptions as those he cobbled together for Belzec and Treblinka.
First, the area he calculates that would be required for each body is not representative of the average size or mass of the victim in these camps. Second, he makes assumptions about the way the remains would have been thrown into the graves in a way that actually wastes the space that was available. Finally, he uses a map that is not scaled as to the size or distance between objects shown on it. Therefore, they cannot be used as Denierbud does to draw conclusions about size and space.
The evidence about the extermination area and the mass graves in the death camp of Sobibor.
Karl Bolender, an SS guard at Sobibor, recalled: “The Jewish working brigade put the corpses into rectangularly boarded trolleys and drove them to the mass grave. A mass grave may have been approx. 60 m long, 20 m wide and 6-7 m deep [about 197 feet long by 66 feet wide by 29 to 23 feet deep.] The side walls were sloped like an embankment to avoid the danger of collapse.” In a later interrogation, Bolden spoke of a second pit: “. . . we put corpses in this second pit even before its completion. Above the first pit a layer of sand was spread. After this pit was completely full, the other corpses had to be put somewhere, even though we were not yet finished with the new pit.”
Bolender’s recollection is in accord with preliminary excavations on the grounds of Sobibor in 2001 conducted by Andrzej Kola, who found seven mass graves, the largest grave of which was 64 meters by 23 feet by 4.5 meters deep (210 feet by 75 feet by 15 feet deep.) The others measured 18 meters by 23 meters by 4.5 meters deep (60 feet by 75 feet by 15 feet deep.)
Ben-Gurion University conducted a thorough archeological study of Sobibor in 2001, 2007 and 2008. They have confirmed the existence of at least seven mass graves. The graves are of varying sizes and they found them to be “heavily mixed with ashes and burnt materials and artifacts.” 
In fact, even today the area around the memorial shows distinct traces of darker green grass indicating the areas of the mass graves. The locations of the seven mass graves can be seen even better from the air. When Isaac Gilead, Yoram Haimi and Wojciech Mazurek carried out investigations on the Sobibor site, they included in their report aerial photos taken of the camp site showing the clearing around the ash memorial and several deeper green areas indicating the mass graves.
Denierbud’s claim that the only mass grave in the death camp of Sobibor was a little larger than a “hen house” is false. He employs the same faulty assumptions he used when calculating the capacity of the mass graves in Belzec and Treblinka, arriving at an inflated volume needed for the mass graves, and then applying his overstated calculations on an unscaled map. There were at least seven mass graves in Sobibor and that was plenty of room in the extermination area for both the graves and the incineration grills.
By User:Merlin (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html), CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/) or CC BY-SA 2.5-2.0-1.0 (http://creativecommons.org/licenses/by-sa/2.5-2.0-1.0)], via Wikimedia Commons
 See “One Third of the Holocaust” at http://www.youtube.com/watch?v=taIaG8b2u8I at approximately 1:48 minutes.
 ‘Vernehmungsniederschrift of Kurt Bolender of 5 June 1961. ZStL, VII, 252/59, Band II,’ p. 194 and ‘Interrogation of Kurt Bolender of 18 December 1963’. Staatsanwaltschaft Dortmund, Band 35, p. 116 as cited by Carlo Mattogno, Thomas Kues and Jürgen Graf in in The “Extermination Camps” of “Aktion Reinhardt,” Part Two, p. 1286.
 “Archeologists find mass graves of Sobibor Nazi death camp,” Ha’aretz (English edition), November 24, 2001 at http://www.fpp.co.uk/Auschwitz/Sobibor/graves_found.html; Mass Graves Confirm Sobibor Holocaust,” The Scotsman, November 26, 2001 at http://www.fpp.co.uk/Auschwitz/Sobibor/Scotsman.html.
 Isaac Gilead, Yoram Haimi and Wojciech Mazurek, “Excavating Nazi Extermination Centres” at www.presentpasts.info/article/view/pp.12/2. You may see these areas clearly marked and numbered at Jonathan Harrison, Robert Muehlenkamp, Jason Myers, Sergey Romanov and Nicholas Terry, Belzec, Sobibor, Treblinka: Holocaust Denial and Operation Reinhard. A Critique of the Falsehoods of Mattogno, Graf and Kues, p. 393 at http://holocaustcontroversies.blogspot.com/2011/12/belzec-sobibor-treblinka-holocaust.html. Select Google Docs, Rapidshare or Archive.org for a PDF version.