How many concentration camps are there?

About 1,500. This staggering figure includes all satellite camps, including temporary camps. There were about 20 main camps (Stammlager).

Most concentration camps had many sub-camps, many of them labour camps that only functioned for a short time. The list below from the German-language Wikipedia is very good. There is a link below to the list issued by the Federal German Ministry of Justice. This can be assumed to be more or less definitive.

(The figure of 1,500 only includes camps run by the SS and related organization. It does not include camps for Soviet prisoners of war or camps for forced labourers imported to Germany from Eastern Europe).

Please see the link for the full list and also the related question.

Wikipedia and other sources name six extermination camps, all located in occupied Poland:

  • Auschwitz II (part only)
  • Belzec
  • Chelmno
  • Majdanek (part only)
  • Sobib√≥r
  • Treblinka II

These six were killing centres and enjoy a kind of canonical status. Many would add Maly Trostenets in Belarus and some include Janowska in Ukraine.

The figure of 1,500 camps does not include camps for forced foreign labourers sent to Germany from the various countries under German rule. Many of these camps, especially those for Poles and Ukrainians, were little better than concentration camps. Nor does the figure include regular POW (prisoner of war) camps.

Note that there were three grades of ordinary Nazi concentration camps. These were, in ascending order of harshness: Grade I (such as Dachau) , Grade II (such as Buchenwald) and Grade III (such as Auschwitz III - aka Buna or Monowitz). Conditions at the Grade III camps were appallingly bad.

In 1944 there were 5.7 million forced foreign workers in Germany, many of whom had been abducted (kidnapped), taken to Germany and forced to work there.

Please see the link beginning with the word Bundesministerium for the full list.

Because the camps were located in all of the occupied countries in some form or another, and because many camps had sub-camps and even the sub-camps were further divided at different labor sites, I doubt that even the Nazi's could answer. Camps existed in Africa and even in the British Channel Islands. Not all camps were giant extermination factories, some were collection and transit points while the vast majority were labor centers with as few as a couple dozen inmates.

Answer

There were ten times more camps than that! Only now as that particular generation die out is the true number starting to be revealed.

" Jewish Virtual Library estimates that the number of Nazi camps was closer to 15,000 in all of occupied Europe"

[From http://en.wikipedia.org/wiki/Nazi_concentration_camps ]

But even that is an estimate: it's worse than that:-

"THIRTEEN years ago, researchers at the United States Holocaust Memorial Museum began the grim task of documenting all the ghettos, slave labor sites, concentration camps and killing factories that the Nazis set up throughout Europe.

What they have found so far has shocked even scholars steeped in the history of the Holocaust.

The researchers have cataloged some 42,500 Nazi ghettos and camps throughout Europe, spanning German-controlled areas from France to Russia and Germany itself, during Hitler's reign of brutality from 1933 to 1945.

The figure is so staggering that even fellow Holocaust scholars had to make sure they had heard it correctly when the lead researchers previewed their findings at an academic forum.....

When the research began in 2000, Dr. Megargee said he expected to find perhaps 7,000 Nazi camps and ghettos, based on postwar estimates. But the numbers kept climbing - first to 11,500, then 20,000, then 30,000, and now 42,500.

The numbers astound: 30,000 slave labor camps; 1,150 Jewish ghettos; 980 concentration camps; 1,000 prisoner-of-war camps; 500 brothels filled with sex slaves; and thousands of other camps used for euthanizing the elderly and infirm, performing forced abortions, "Germanizing" prisoners or transporting victims to killing centers.

In Berlin alone, researchers have documented some 3,000 camps and so-called Jew houses, while Hamburg held 1,300 sites.

Dr. Dean, a co-researcher, said the findings left no doubt in his mind that many German citizens, despite the frequent claims of ignorance after the war, must have known about the widespread existence of the Nazi camps at the time.

"You literally could not go anywhere in Germany without running into forced labor camps, P.O.W. camps, concentration camps," he said. "They were everywhere."

[From article "The Holocaust Just Got More Shocking' at http://www.nytimes.com/2013/03/03/sunday-review/the-holocaust-just-got-more-shocking.html?pagewanted=all&_r=0 ]

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35 main and 100's of smaller
There were about 35 main and 1000 smaller concentration camps during World War 2 and there were 6 extermination (death) camps.