Run and build numbers

Azure DevOps Services | Azure DevOps Server 2022 - Azure DevOps Server 2019

This article explains how Azure Pipelines build numbers and run numbers are constructed, and how you can customize them in your pipelines.

The run number is used to identify a specific execution of a pipeline or build. The build number is synonymous with the run number.

If you don't specify a build name in YAML pipelines, or you leave the Name field blank in Classic pipelines, your run gets a unique integer as its name. You can give runs more useful names that are meaningful to your team. You can use a combination of tokens, variables, and underscore characters in build names.

In YAML pipelines, the build name property is called name and must be at the root level of a pipeline. Items specified at the root level of a YAML file are pipeline properties.


The name property doesn't work in template files.

The following example code outputs a customized build number like project_def_master_20240828.1.

name: $(TeamProject)_$(Build.DefinitionName)_$(SourceBranchName)_$(Date:yyyyMMdd).$(Rev:r)

  - script: echo '$(Build.BuildNumber)'

Run number

The default value for a run number in Azure Pipelines is $(Date:yyyyMMdd).$(Rev:r). $(Rev:r) is a special variable format that only works in the build number field. When a build completes, if nothing else in the build number changed, the Rev integer value increases by one.

$(Rev:r) resets to 1 when any other part of the build number changes. For example, if you configure your build number format as $(Build.DefinitionName)_$(Date:yyyyMMdd).$(Rev:r), the build number resets when the date changes.

If the previous build number was MyBuild_20230621.1, the next build number that day is MyBuild_20230621.2. The first build number the next day is MyBuild_20230622.1.

$(Rev:r) also resets to 1 if you change the build number to indicate a version change. For example, if your build format is 1.0.$(Rev:r) and your last build number was 1.0.3, if you change the build number to 1.1.$(Rev:r), the next build number is 1.1.1.


Consider the following data for a build run:

  • Project name: Fabrikam
  • Pipeline name: CIBuild
  • Branch: main
  • Build ID/Run ID: 752
  • Date: May 6, 2024
  • Time: 9:07:03 PM
  • One run completed earlier today.

If you specify the following build number format, the second run on May 6, 2024 is named Fabrikam_CIBuild_main_20240506.2.



The following table shows how each token resolves, based on the previous example. You can use these tokens only to define run numbers. They don't work anywhere else in a pipeline.

Token Example value Notes
$(Build.DefinitionName) CIBuild The pipeline name can't contain invalid or whitespace characters.
$(Build.BuildId) 752 $(Build.BuildId) is an internal, immutable ID, also called the Run ID, that is unique across the Azure DevOps organization.
$(DayOfMonth) 6
$(DayOfYear) 126
$(Hours) 21
$(Minutes) 7
$(Month) 5
$(Rev:r) 2 The third daily run is 3, and so on. Use $(Rev:r) to ensure that every completed build has a unique name.
$(Date:yyyyMMdd) 20240506 You can specify other date formats such as $(Date:MMddyy).
$(Seconds) 3
$(SourceBranchName) main
$(TeamProject) Fabrikam
$(Year:yy) 24
$(Year:yyyy) 2024


If you want to show prefix zeros in the run number, you can add more r characters to the Rev token. For example, specify $(Rev:rr) if you want the Rev number to begin with 01, 02, and so on.

If you use a zero-padded Rev as part of a version numbering scheme, be aware that some pipeline tasks or popular tools, like NuGet packages, remove the leading zeros. This behavior causes a version number mismatch in the artifacts that are produced.


If you use an expression to set the build number, you can't use some tokens, because their values aren't set at the time expressions are evaluated. These tokens include $(Build.BuildId), $(Build.BuildURL), and $(Build.BuildNumber).


You can use user-defined and predefined variables in your build number. For example, if you define My.Variable, you can specify the following number format:


In the preceding example, the first four variables are predefined. For information on how to define user variables, see Set variables in pipelines.


How large can a run number be, and what characters can I use?

Run numbers can be up to 255 characters. You can't use the characters ", /, :, <, >, ', |, ?, @, or *, and you can't end the number with ..

What time zone are the build number time values expressed in?

The time zone is UTC.

The time zone is the same as the time zone of the operating system of the machine that runs your application tier server.

How can I set the build number dynamically with conditions?

You can use variables as part of your run number. In the following example, the variable why is used as part of the run number, and its value changes depending on the Build.Reason.

  - name: why
    ${{ if eq(variables['Build.Reason'], 'PullRequest') }}:
      value: pr
    ${{ elseif eq(variables['Build.Reason'], 'Manual' ) }}:
      value: manual
    ${{ elseif eq(variables['Build.Reason'], 'IndividualCI' ) }}:
      value: indivci
    ${{ else }}:
      value: other

name: $(TeamProject)_$(SourceBranchName)_$(why)_$(Date:yyyyMMdd).$(Rev:.r)

  vmImage: 'ubuntu-latest'

- script: echo '$(Build.BuildNumber)'

How can I reference the run number variable within a script?

You can define a new variable that includes the run number, or call the run number directly. In the following example, $(MyRunNumber) is a new variable that includes the run number. You can call the run number variable by using MyRunNumber or $(Build.BuildNumber).

# Set MyRunNumber
  MyRunNumber: '1.0.0-CI+$(Build.BuildNumber)'

- script: echo $(MyRunNumber)
- script: echo $(Build.BuildNumber)

Define variables