cat countedit

count provides quick access to the document count of the entire cluster, or individual indices.

GET /_cat/count?v

Looks like:

epoch      timestamp count
1475868259 15:24:19  121

Or for a single index:

GET /_cat/count/twitter?v
epoch      timestamp count
1475868259 15:24:20  120

The document count indicates the number of live documents and does not include deleted documents which have not yet been cleaned up by the merge process.