Imp.metric

An array of Metric objects reporting measured properties of the impression, such as recent viewability or click-through rate, so buyers can price it. Added in OpenRTB 2.5.

Currentobject arrayOptionalSince 2.5

Field facts

Path: imp.metric
Object: Imp
Type: object array
Requirement: Optional
Added: OpenRTB 2.5
Spec section: 3.2.4

How it is used

Exchanges choose which metric names they send and publish that list to buyers. A bidder that meets a name it does not know should ignore that entry rather than reject the impression.

Example

Where the field sits in a payload, with everything else left out:

{
  "id": "req-1",
  "imp": [
    {
      "metric": [
        {
          "type": "viewability",
          "value": 0.72,
          "vendor": "EXCHANGE"
        }
      ]
    }
  ]
}

Version history

Added in OpenRTB 2.5, and present in the latest snapshot. The table shows how each version's spec text types the field.

Versions	Type in the spec	Required	Deprecated
2.5 to 2.6-202606	object array	No	No

Versioned rules that name this field

openrtb.2.5.imp.metric OpenRTB 2.5 introduced the Metric object for historical viewability, CTR, and similar signals.

Related fields

Other Imp fields

For a walkthrough of the whole object, read Bid request anatomy.