How can I check the size of a collection?

To view the size of a collection and other information, use the db.collection.stats() method from the mongo shell.

The following example issues db.collection.stats() for the orders collection:


To view specific measures of size, use these methods:

db.collection.dataSize() # data size in bytes for the collection.
db.collection.storageSize() # allocation size in bytes, including unused space.
db.collection.totalSize() # the data size plus the index size in bytes.
db.collection.totalIndexSize() # the index size in bytes.

Also, the following scripts print the statistics for each database and collection:

db._adminCommand("listDatabases").databases.forEach(function (d) {mdb = db.getSiblingDB(; printjson(mdb.stats())})

db._adminCommand("listDatabases").databases.forEach(function (d) {mdb = db.getSiblingDB(; mdb.getCollectionNames().forEach(function(c) {s = mdb[c].stats(); printjson(s)})})

How can I check the size of indexes?

To view the size of the data allocated for an index, use one of the following procedures in the mongo shell:

Use the db.collection.stats() method using the index namespace. To retrieve a list of namespaces, issue the following command:


Check the value of indexSizes in the output of the db.collection.stats() command.

Example: Issue the following command to retrieve index namespaces:


The command returns a list similar to the following:

{"name" : "test.orders"}
{"name" : "test.system.indexes"}
{"name" : "test.orders.$_id_"}

View the size of the data allocated for the orders.$_id_ index with the following sequence of operations:

use test