I am creating this blog post as a quick reminder of how to check the size of my database:

> db.stats(1024)

{
"db" : "sqdev",
"collections" : 25,
"objects" : 31509618,
"avgObjSize" : 704.2919142974059,
"dataSize" : 21671844,
"storageSize" : 24783691,
"numExtents" : 163,
"indexes" : 44,
"indexSize" : 25900801,
"fileSize" : 64915456,
"nsSizeMB" : 16,
"ok" : 1
}

Per the documentation @ 10Gen, the results of this command return kilobytes[1]. So just divide

everything by (1024^2) to get gigobytes.

31509618/(1024^2) = ~31Gs of data

25900801/(1024^2) = ~25G of indexes (WTF??)

[1] http://docs.mongodb.org/manual/reference/database-statistics/