New in version 1.4.



Count the number of documents that match the filter criteria.

function countDocuments(array|object $filter = [], array $options = []): integer

This method has the following parameters:

Parameter Type Description
$filter array|object Optional. The filter criteria that specifies the documents to count.
$options array Optional. An array specifying the desired options.

The $options parameter supports the following options:

Option Type Description
collation array|object

Optional. Collation allows users to specify language-specific rules for string comparison, such as rules for lettercase and accent marks. When specifying collation, the locale field is mandatory; all other collation fields are optional. For descriptions of the fields, see Collation Document.

If the collation is unspecified but the collection has a default collation, the operation uses the collation specified for the collection. If no collation is specified for the collection or for the operation, MongoDB uses the simple binary comparison used in prior versions for string comparisons.

comment mixed

Optional. Enables users to specify an arbitrary comment to help trace the operation through the database profiler, currentOp output, and logs.

The comment can be any valid BSON type for server versions 4.4 and above. Earlier server versions only support string values.

hint string|array|object Optional. The index to use. Specify either the index name as a string or the index key pattern as a document. If specified, then the query system will only consider plans using the hinted index.
limit integer Optional. The maximum number of matching documents to return.
maxTimeMS integer Optional. The cumulative time limit in milliseconds for processing operations on the cursor. MongoDB aborts the operation at the earliest following interrupt point.
readConcern MongoDB\Driver\ReadConcern

Optional. Read concern to use for the operation. Defaults to the collection’s read concern.

It is not possible to specify a read concern for individual operations as part of a transaction. Instead, set the readConcern option when starting the transaction with startTransaction.

readPreference MongoDB\Driver\ReadPreference Optional. Read preference to use for the operation. Defaults to the collection’s read preference.
session MongoDB\Driver\Session Optional. Client session to associate with the operation.
skip integer Optional. The number of matching documents to skip before returning results.

Return Values

The number of documents matching the filter criteria.


MongoDB\Exception\UnexpectedValueException if the command response from the server was malformed.

MongoDB\Exception\UnsupportedException if options are used and not supported by the selected server (e.g. collation, readConcern, writeConcern).

MongoDB\Exception\InvalidArgumentException for errors related to the parsing of parameters or options.

MongoDB\Driver\Exception\RuntimeException for other errors at the driver level (e.g. connection errors).


Internally, this method uses the $group aggregation pipeline operator to obtain the result. If a filter parameter is given, this is converted into a $match pipeline operator. Optional $skip and $limit stages are added between $match and group if present in the options.


This method counts documents on the server side. To obtain an approximate total number of documents without filters, the MongoDB\Collection::estimatedDocumentCount() method can be used. This method estimates the number of documents based on collection metadata, thus sacrificing accuracy for performance.

Since this method uses an aggregation pipeline, some query operators accepted within a MongoDB\Collection::count() filter cannot be used. Consider the following alternatives to these restricted operators:

Restricted Alternative Syntax
$near $geoWithin with $center
$nearSphere $geoWithin with $centerSphere
$where $expr

When evaluating query criteria, MongoDB compares types and values according to its own comparison rules for BSON types, which differs from PHP’s comparison and type juggling rules. When matching a special BSON type the query criteria should use the respective BSON class in the driver (e.g. use MongoDB\BSON\ObjectId to match an ObjectId).