﻿---
title: Max bucket aggregation
description: A sibling pipeline aggregation which identifies the bucket(s) with the maximum value of a specified metric in a sibling aggregation and outputs both the...
url: https://www.elastic.co/elastic/docs-builder/docs/2452/reference/aggregations/search-aggregations-pipeline-max-bucket-aggregation
---

# Max bucket aggregation
A sibling pipeline aggregation which identifies the bucket(s) with the maximum value of a specified metric in a sibling aggregation and outputs both the value and the key(s) of the bucket(s). The specified metric must be numeric and the sibling aggregation must be a multi-bucket aggregation.

## Syntax

A `max_bucket` aggregation looks like this in isolation:
```js
{
  "max_bucket": {
    "buckets_path": "the_sum"
  }
}
```



| Parameter Name | Description                                                                                                                                                                                                                          | Required | Default Value |
|----------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------|---------------|
| `buckets_path` | The path to the buckets we wish to find the maximum for (see [`buckets_path` Syntax](/elastic/docs-builder/docs/2452/reference/aggregations/pipeline#buckets-path-syntax) for more details)                                          | Required |               |
| `gap_policy`   | The policy to apply when gaps are found in the data (see [Dealing with gaps in the data](/elastic/docs-builder/docs/2452/reference/aggregations/pipeline#gap-policy) for more details)                                               | Optional | `skip`        |
| `format`       | [DecimalFormat pattern](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/text/DecimalFormat.html) for theoutput value. If specified, the formatted value is returned in the aggregation’s`value_as_string` property | Optional | `null`        |

The following snippet calculates the maximum of the total monthly `sales`:
```json

{
  "size": 0,
  "aggs": {
    "sales_per_month": {
      "date_histogram": {
        "field": "date",
        "calendar_interval": "month"
      },
      "aggs": {
        "sales": {
          "sum": {
            "field": "price"
          }
        }
      }
    },
    "max_monthly_sales": {
      "max_bucket": {
        "buckets_path": "sales_per_month>sales" <1>
      }
    }
  }
}
```

And the following may be the response:
```json
{
   "took": 11,
   "timed_out": false,
   "_shards": ...,
   "hits": ...,
   "aggregations": {
      "sales_per_month": {
         "buckets": [
            {
               "key_as_string": "2015/01/01 00:00:00",
               "key": 1420070400000,
               "doc_count": 3,
               "sales": {
                  "value": 550.0
               }
            },
            {
               "key_as_string": "2015/02/01 00:00:00",
               "key": 1422748800000,
               "doc_count": 2,
               "sales": {
                  "value": 60.0
               }
            },
            {
               "key_as_string": "2015/03/01 00:00:00",
               "key": 1425168000000,
               "doc_count": 2,
               "sales": {
                  "value": 375.0
               }
            }
         ]
      },
      "max_monthly_sales": {
          "keys": ["2015/01/01 00:00:00"], 
          "value": 550.0
      }
   }
}
```