In short: According to UiPath, an unattended robot needs at least 2 CPU cores at 1.8 GHz and 4 GB of available RAM; 4 cores at 2.4 GHz and 8 GB are recommended. If several robots run at the same time on one Windows Server, multiply these values by the number of robots. The machine must run permanently and must never go to sleep, otherwise Orchestrator cannot start jobs on it.
Attended or unattended: what's the difference?
- Attended robots work alongside a person. An employee starts the automation on their own computer, for example from UiPath Assistant, and the robot runs in that person's Windows session.
- Unattended robots work on their own. UiPath Orchestrator starts jobs from a schedule, a queue or a trigger, signs in to the machine itself and runs without supervision.
That is why unattended robots need a machine that is always reachable. An office laptop isn't. A Windows Server in a datacenter, or a permanently running VM, is.
Hardware requirements per robot
UiPath lists these values for one robot executing a job:
| Resource | Minimum | Recommended |
|---|---|---|
| CPU | 2 × 1.8 GHz, 64-bit | 4 × 2.4 GHz, 64-bit |
| RAM | 4 GB of available memory | 8 GB of available memory |
Source: UiPath Robot – Hardware and software requirements
Two caveats from the same source:
- The values cover the automation only. Windows, browsers, Excel, SAP or any other application the robot drives need resources on top.
- For live streaming and recording of robot sessions, UiPath requires the recommended values.
UiPath also notes that automations using Document Understanding may need additional RAM.
Several robots on one server (high-density)
On Windows Server, several robots can run at the same time in separate sessions. UiPath calls these high-density robots. The hardware requirements multiply by the number of concurrent sessions (runtimes) configured on the machine template in Orchestrator.
Example from the UiPath documentation: three concurrent robots need at least six 1.8 GHz cores and 12 GB of RAM.
For planning:
| Concurrent robots | Minimum (CPU / RAM) | Recommended (CPU / RAM) |
|---|---|---|
| 1 | 2 cores / 4 GB | 4 cores / 8 GB |
| 2 | 4 cores / 8 GB | 8 cores / 16 GB |
| 3 | 6 cores / 12 GB | 12 cores / 24 GB |
| 4 | 8 cores / 16 GB | 16 cores / 32 GB |
Calculated from UiPath's values; add headroom for Windows and your applications.
According to UiPath, high-density robots are available on Windows only. Multiple concurrent user sessions on Windows Server use Remote Desktop Services, which need separate access licences: RDS CALs in your own datacenter, or, on rented servers, usually monthly per-user SPLA licences (SALs) billed by the hosting provider. Clarify this before you plan.
Which Windows version?
UiPath supports robots on Windows Server 2016, 2019, 2022 and 2025, among others. According to UiPath, Windows Server Core (without a graphical interface) can only run background jobs, not automations that interact with the user interface. Most RPA processes therefore need Windows Server with Desktop Experience. .NET Framework 4.7.2 or later is also required.
Checklist for a stable unattended robot
- Disable sleep and power saving. The machine must always be on, or the robot won't accept jobs.
- Fix the screen resolution. UI automations depend on a fixed resolution. Set it in the robot settings in Orchestrator.
- Log off properly. If the robot user's RDP session is disconnected but not logged off, the robot cannot open a new session. Sign out after maintenance instead of just closing the window.
- Schedule Windows updates. A reboot in the middle of a job aborts it. Use a fixed maintenance window outside your robot schedules.
- Use dedicated resources. On oversold hosts performance fluctuates, and time-sensitive selectors run into timeouts.
- Back up the whole machine. Not just your process files: applications, settings and certificates matter too.
Your own server, cloud robots or a rented Windows Server?
| Option | Advantage | Drawback |
|---|---|---|
| Own server in the office | full control | hardware, power, updates and backups are yours; outages during power or internet failures |
| Rented managed Windows Server | datacenter, updates and backups handled by the provider, full admin access | monthly cost; Windows licence must be included or added |
GB Hosting offers Windows Servers in Germany with the Windows licence included, administrator RDP access and daily snapshot backups, built for unattended robots. More: UiPath server hosting.
FAQ
How much RAM does a UiPath robot need?
At least 4 GB of available memory per concurrently running robot; 8 GB is recommended. Windows and the applications the robot drives need memory on top.
Can an unattended robot run on a virtual machine?
Yes. UiPath supports robots on virtual machines, including in the cloud. The VM must run permanently and must not go to sleep.
Do I need a separate server for every robot?
No. Windows Server can run several robots at the same time (high-density), provided it has enough resources for all sessions.