# Machine Sizes and Costs
> To run processes using serverless robots, you must have the required amount of [platform units](https://docs.uipath.com/orchestrator/automation-cloud/latest/user-guide/consuming-platform-units#consuming-platform-units) available for the tenant in which the process needs to run.
## Unified Pricing licensing
To run processes using serverless robots, you must have the required amount of [platform units](https://docs.uipath.com/orchestrator/automation-cloud/latest/user-guide/consuming-platform-units#consuming-platform-units) available for the tenant in which the process needs to run.
The amount of platform units that are consumed depends on:
* the type of environment - test environments have lower platform units consumption than production environments;
* the size of the serverless robot machine;
* the number of minutes it takes to execute a job.
The following machine sizes are available:
| Machine size | Testing platform units/minute 1 | Production platform units/minute |
| --- | --- | --- |
| Small (1GB) | 0.1 | 0.2 |
| Standard (2GB) | 0.2 | 0.4 |
| Medium (4GB) | 0.4 | 0.8 |
| Large (10 GB) | 1 | 2 |
1 You must be on the **Enterprise**, **Pro**, or **Pro Trial** licensing plan to use this feature.
## Flex licensing
To run processes using serverless robots, you must have the required amount of RUs ([robot units](https://docs.uipath.com/overview/other/latest/overview/service-licensing#robot-units)) available for the tenant in which the process needs to run.
The amount of RUs that are consumed depends on:
* the type of environment - test environments have lower RU consumption than production environments;
* the size of the serverless robot machine;
* the number of minutes it takes to execute a job.
The following machine sizes are available:
| Machine size | Testing RUs/minute 1 | Production RUs/minute |
| --- | --- | --- |
| Small (1GB) | 0.5 | 1 |
| Standard (2GB) | 1 | 2 |
| Medium (4GB) | 2 | 4 |
| Large (10 GB) | 5 | 10 |
1 You must be on the **Enterprise**, **Pro**, or **Pro Trial** licensing plan to use this feature.
:::note
When running Apps or Action Apps built in Studio Web, small and standard serverless machine sizes do not consume Robot Units. Medium and large machine sizes consume Robot Units at the rates listed in the table above.
:::
## Choosing the machine size
Because each process has particular needs, you set the machine size in the configuration of a process.
For any cross-platform process, the **Cloud Robot - Serverless** list is available on the **Additional Settings** tab when [creating or editing a process](https://docs.uipath.com/orchestrator/automation-cloud/latest/user-guide/managing-processes).
Figure 1. Choosing the machine size
The option is available for all cross-platform processes, which are candidates for being run using serverless robots, but the option has no effect unless it is executed by a serverless robot.
## Automatic machine size selection
All your cross-platform processes have the **Cloud Robot - Serverless** option set to **Automatic** by default. This setting selects the appropriate machine size for running the process using serverless robots.
The amount of robot units consumed to run the process is based on the machine size and the number of minutes it takes to run.
When automatically choosing the size, the criteria listed in the below table are evaluated in order. As soon as one criterion is satisfied, the corresponding machine size is chosen and the remaining criteria are not evaluated.
| Order | Criterion | Machine size |
| --- | --- | --- |
| 1 | Remote debugging job | Medium |
| 2 | Process depends on [UI Automation](https://docs.uipath.com/studio/docs/ui-automation) OR Process depends on the [UiPath Document Understanding activities](https://docs.uipath.com/document-understanding/docs/activities-packages) | Standard |
| 3 | Other unattended process | Small |