How to Convert a Windows SID to a Username

What a SID Is and Why You Might Need to Convert It

A SID (Security Identifier) is a unique code that Windows assigns to every user account on a computer or network. It looks like this: S-1-5-21-3623811015-3361044348-30300820-1013. While Windows uses SIDs internally to manage permissions and security, you as a homeowner or small business owner will usually see usernames instead — they are easier to read and remember.

You might encounter a SID when you are troubleshooting file permissions, reviewing security logs, or managing user accounts on a shared computer. If you see a SID in a file's properties or in a security report and need to know which person it belongs to, you will need to convert it back to the username.

Key Takeaways

Windows stores user accounts as SIDs internally, but you can convert them back to usernames using built-in tools or the command line.
The quickest method on most home computers is to right-click a file, check Properties, then the Security tab to see usernames instead of SIDs.
If you need to convert many SIDs at once, the command line tool wmic or PowerShell can do the work faster than clicking through menus.
Some SIDs belong to system accounts (like SYSTEM or LOCAL SERVICE) rather than real user accounts, so not every SID will convert to a person's name.

Using File Properties to See the Username Behind a SID

The simplest way to convert a SID to a username is to look at the file or folder where you saw the SID. Right-click the file or folder, select Properties, then go to the Security tab. Click Edit to open the permissions window.

In the permissions list, you will see usernames instead of SIDs. If the SID you are looking for appears in this list, Windows will show you the username next to it. This method works on Windows 10 and Windows 11 for any file or folder on your computer.

This approach only works if the SID has permissions on that particular file. If you need to find a SID that is not tied to any file you can access, you will need to use a command-line tool instead.

Converting SIDs Using the Command Line (wmic)

If you need to convert a SID without looking at file permissions, open the Command Prompt as an administrator. Press the Windows key, type cmd, right-click Command Prompt, and select Run as administrator.

Type this command and replace the SID with the one you want to convert:

wmic useraccount where sid="S-1-5-21-3623811015-3361044348-30300820-1013" get name

Press Enter. Windows will display the username that matches that SID, or return no results if the SID does not exist on your computer. This method works for any SID on your local machine, whether or not it has file permissions.

Using PowerShell for Batch Conversions

If you have many SIDs to convert at once, PowerShell is faster than running the wmic command repeatedly. Open PowerShell as an administrator: press the Windows key, type powershell, right-click Windows PowerShell, and select Run as administrator.

Use this command to convert a single SID:

$sid = New-Object System.Security.Principal.SecurityIdentifier("S-1-5-21-3623811015-3361044348-30300820-1013")$user = $sid.Translate([System.Security.Principal.NTAccount])$user.Value

For multiple SIDs, save them in a text file (one SID per line) and use a loop to convert them all at once. This is most useful if you are managing permissions across many files or troubleshooting a security issue that involves multiple accounts.

When a SID Does Not Convert to a Username

Not every SID belongs to a real user account. Windows reserves certain SIDs for system functions. Common ones include:

S-1-5-18 (SYSTEM)
S-1-5-19 (LOCAL SERVICE)
S-1-5-20 (NETWORK SERVICE)
S-1-1-0 (Everyone)

If you run a conversion command and get no result, the SID might be one of these built-in accounts, or it might belong to a user account that has been deleted from the computer. Deleted accounts leave behind "orphaned" SIDs in file permissions — the account no longer exists, but the SID remains tied to the file.

If you see an orphaned SID in a file's permissions and want to clean it up, you can remove it by editing the file's security settings and deleting that entry from the permissions list.

Checking SIDs on a Network or Domain

If your computer is part of a workplace network or domain, SIDs from other computers on the network will not convert using the methods above. Your computer only has a local database of its own user accounts.

To convert a SID from another computer on the network, you need access to that computer or to ask your network administrator. If you are managing a small home network and need to identify a user on a different machine, the easiest approach is to log into that computer directly and run the conversion command there.

For workplace networks, your IT department has tools to look up SIDs across the entire domain. If you work in an office and need a SID converted, contact your IT help desk with the SID and they can tell you which account it belongs to.

Frequently Asked Questions

Why does Windows use SIDs instead of just usernames?

SIDs are unique identifiers that stay the same even if you rename a user account. If Windows used only usernames, changing a name would break all the permissions tied to that account. SIDs solve this by staying constant while usernames can change.

Can I see all the SIDs on my computer at once?

Yes. In PowerShell as administrator, type Get-LocalUser | Select-Object Name, SID to see every local user account and its SID. This is useful if you want to build a reference list or check whether a particular SID exists on your machine.

What if the wmic command does not work?

The wmic tool is built into Windows but may be disabled on some systems. If it does not work, use the PowerShell method instead — it is more reliable on newer versions of Windows 10 and Windows 11. Make sure you are running as administrator either way.

Can I convert a SID from a Mac or Linux computer?

No. SIDs are specific to Windows. Mac and Linux use different systems to identify user accounts. If you need to manage users across different operating systems, you will need to use the native tools for each one.

Is it safe to delete a SID from a file's permissions?

Yes, if the SID is orphaned (the account no longer exists). Removing it will not affect anything. However, if the SID belongs to an active account that you still need to have access to the file, deleting it will lock that person out. Always verify what account a SID belongs to before you remove it.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.