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Returns statistics that reflect the use state of a single database.

The db.stats() method is a wrapper around the dbStats database command.

This method is available in deployments hosted in the following environments:

  • MongoDB Atlas: The fully managed service for MongoDB deployments in the cloud


This command has limited support in M0, M2, and M5 clusters. For more information, see Unsupported Commands.

The db.stats() method has the following optional parameters:


Optional. The scale factor for the various size data. The scale defaults to 1 to return size data in bytes. To display kilobytes rather than bytes, specify a scale value of 1024.

If you specify a non-integer scale factor, MongoDB uses the integer part of the specified factor. For example, if you specify a scale factor of 1023.999, MongoDB uses 1023 as the scale factor.

Starting in version 4.2, the output includes the scaleFactor used to scale the size values.


Optional. To return information on free space allocated to collections, set freeStorage to 1.

If the instance has a large number of collections or indexes, obtaining free space usage data may cause processing delays. To gather db.stats() data without free space details, either set freeStorage to 0 or do not include the parameter.

The db.stats() method returns a document with statistics about the database system's state. A complete listing, including freeStorage details, resembles the following:

db: 'test',
collections: 2,
views: 0,
objects: 1689,
avgObjSize: 52.56542332741267,
dataSize: 86.7021484375,
storageSize: 100,
freeStorageSize: 32,
indexes: 2,
indexSize: 116,
indexFreeStorageSize: 36,
totalSize: 216,
totalFreeStorageSize: 68,
scaleFactor: 1024,
fsUsedSize: 60155820,
fsTotalSize: 61255492,
ok: 1,
'$clusterTime': {
clusterTime: Timestamp({ t: 1646085664, i: 1 }),
signature: {
hash: Binary(Buffer.from("0000000000000000000000000000000000000000", "hex"), 0),
keyId: Long("0")
operationTime: Timestamp({ t: 1646085664, i: 1 })

For an explanation of the output, see Output.

After an unclean shutdown of a mongod using the Wired Tiger storage engine, count and size statistics reported by db.stats() may be inaccurate.

The amount of drift depends on the number of insert, update, or delete operations performed between the last checkpoint and the unclean shutdown. Checkpoints usually occur every 60 seconds. However, mongod instances running with non-default --syncdelay settings may have more or less frequent checkpoints.

Run validate on each collection on the mongod to restore statistics after an unclean shutdown.

After an unclean shutdown:

To run on a replica set member, dbStats operations require the member to be in PRIMARY or SECONDARY state. If the member is in another state, such as STARTUP2, the operation errors.

To to return values in kilobytes, set the scale to 1024:



The scale factor rounds values to whole numbers.

To return a single value, such as indexSize, append the field name to db.stats().


The output shows the difference between the original and scaled values.


To return information on free space allocated to collections, pass the freeStorage parameter to db.stats().

The following example returns the indexFreeStorageSize in kilobytes:

db.stats( { freeStorage: 1, scale: 1024 } ).indexFreeStorageSize