Right, yes, as far as I know Elasticsearch doesn't track the total size of documents indexed. It's a bit of a tricky thing to measure accurately: the distributed nature of the system means that in general different shards will have indexed different sets of documents at any given point in time, and the machinery to track this statistic correctly across shard failures and primary relocations would be quite complicated. Perhaps there's a way to get an approximate answer with an aggregation? Or you could track this statistic externally?