Counting Documents in MongoDB

countDocuments() (Recommended)

Counts the number of documents matching a filter — this is the modern, recommended way to count.

db.employees.countDocuments()
db.employees.countDocuments({ age: { $gte: 22 } })

count() (Deprecated)

The older count() method still works but prints a deprecation warning — prefer countDocuments() in new code.

db.employees.count()
// DeprecationWarning: Collection.count() is deprecated.
// Use countDocuments or estimatedDocumentCount.

db.employees.find({ age: { $gte: 22 } }).count()

itcount()

A cursor method that counts documents by actually iterating the cursor. It's mainly used when you already have a cursor from find() and want its size directly.

db.employees.find().itcount()
db.employees.find({ age: 24 }).itcount()

Common Errors & Troubleshooting

• Seeing a DeprecationWarning for count() — this is expected; it still works, but switch to countDocuments() in new code to avoid it entirely.
• countDocuments() seeming slow on a huge collection — unlike the old estimated count, countDocuments() performs a real scan matching your filter; for an unfiltered total-row-count on a huge collection, estimatedDocumentCount() is much faster (though less precise, since it reads collection metadata instead of scanning).
• Counting after a cursor has already been iterated — calling itcount() (or any count) on a cursor that's already been fully read returns 0, since there's nothing left to iterate; re-run the query to get a fresh cursor.

Key Takeaways

• Use countDocuments() for new code — it's accurate and not deprecated.
• count() still runs but MongoDB nudges you toward countDocuments() instead.
• itcount() is a cursor-level method, useful when you're already holding a cursor.