# How to aggregate based on the number of items in a field? **URL:** \ **Category:** Elasticsearch\ **Created:** [August 27, 2021, 9:31am UTC](https://discuss.elastic.co/t/how-to-aggregate-based-on-the-number-of-items-in-a-field/282650 "2021-08-27T09:31:19Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Xi\_Ern\_Tee](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/xi_ern_tee/32/93816_2.png) [@Xi\_Ern\_Tee](https://discuss.elastic.co/u/Xi_Ern_Tee)\ **Post date:** [August 27, 2021, 9:31am UTC](https://discuss.elastic.co/t/how-to-aggregate-based-on-the-number-of-items-in-a-field/282650/1 "2021-08-27T09:31:19Z")
On Elasticsearch I have a field named `Itinerary` that can contain multiple values (from 1 up to 6), for example in the picture below there's 2 items in the field. ![12333](https://us1.discourse-cdn.com/elastic/original/3X/4/a/4a636ee656ab7d22af16803e94db20e44cca6448.png) Is there a way I can aggregate based on the number of items in the field? Having something like: ```auto 1 item : 2 2 item : 4 ... ``` ---
**Author:** ![spinscale](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/spinscale/32/25011_2.png) [@spinscale](https://discuss.elastic.co/u/spinscale)\ **Post date:** [August 30, 2021, 11:25am UTC](https://discuss.elastic.co/t/how-to-aggregate-based-on-the-number-of-items-in-a-field/282650/2 "2021-08-30T11:25:00Z")
I would go with an [ingest processor](https://www.elastic.co/guide/en/elasticsearch/reference/7.14/ingest-processors.html) that calculates the size of the number of fields before indexing. This way, querying stays fast. If you just want to test this feature, try a [runtime field](https://www.elastic.co/guide/en/elasticsearch/reference/7.14/runtime.html) doing that calculation, so that you can filter on it - and even replace it with an indexed field later without replacing your query. Hope this helps! ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [September 27, 2021, 11:25am UTC](https://discuss.elastic.co/t/how-to-aggregate-based-on-the-number-of-items-in-a-field/282650/3 "2021-09-27T11:25:20Z")
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