How can I know average value of field "elapsed.time"

I have my document with field "elapsed.time" I have to know average value of this field.
Many thanks for helping me!!!

You can use the avg aggregation, see

have a look at, this should achieve what you are after

When i execute this aggs:
"aggs" : {
"avg_time" : {
"avg" : {
"field" : "elapsed.time"
I get answer
"hits": {
"total": 17776184,
"max_score": 1,
"hits": [......]
I wonder where is average value?

You should have an aggs element in the json response, it will be there.

Ok, I've found it in the end of JSON response
Many thanks!