Is it a Virus?
NO - Safe
Must be in Program Files\SumatraPDF\SumatraPDF.exe or C:\Program Files (x86)\SumatraPDF\SumatraPDF.exe
Warning
Most processes are normal
If you see multiple SumatraPDF.exe processes, they may correspond to separate document windows or background tasks such as printing.
Can I Disable?
YES
Close Sumatra when not in use; you can disable startup via Windows Task Manager -> Startup.
What is SumatraPDF.exe?
sumatra.exe is the main executable for Sumatra PDF Viewer, a lightweight, open-source PDF reader designed for fast startup and minimal resource use. It focuses on essential features like viewing, searching, and printing PDFs without bloat or heavy plugins.
It runs as a small, primarily single-process application that renders PDF pages using Windows APIs and a simple rendering pipeline. Sumatra aims for stability and speed, avoiding multi-process overhead found in larger readers while still delivering reliable document viewing.
Quick Fact: SumatraPDF was designed for speed and portability; it opens PDFs quickly and uses very little memory compared with heavier PDF readers.
Types of Sumatra Processes
- Main Process: The primary Sumatra PDF Viewer window and UI
- Updater/Background Tasks: Background tasks such as update checks and settings monitoring
- Printer/Print Job: Handles print operations initiated from Sumatra
- External Helper Process: Auxiliary tasks that may run for rendering or compatibility
Is sumatra.exe Safe?
Yes, sumatra.exe is safe when it's the legitimate file from SumatraPDF Project downloaded from official sources.
Is sumatra.exe a Virus or Malware?
The real sumatra.exe is NOT a virus. However, malware can disguise itself with similar names.
How to Tell if sumatra.exe is Legitimate or Malware
- File Location: Must be in
C:\Program Files\SumatraPDF\SumatraPDF.exe or C:\Program Files (x86)\SumatraPDF\SumatraPDF.exe. Any sumatraPDF.exe elsewhere is suspicious.
- Digital Signature: Right-click the process in Task Manager -> Open file location -> Right-click SumatraPDF.exe -> Properties -> Digital Signatures. Should show "SumatraPDF Project".
- Resource Usage: Normally minimal: a few MB memory and low CPU when idle. Unusually high usage with no PDF open is suspicious.
- Behavior: SumatraPDF should launch only when you open a PDF or print. If it starts unexpectedly or runs continuously in the background, scan for malware.
Red Flags: If sumatra.exe is located in unusual folders (Temp, AppData), runs without opening a PDF, has no valid signature, or uses resources constantly, scan with antivirus. Beware of similarly named files like "sumatra32.exe" from untrusted sources.
Why Is sumatra.exe Running on My PC?
sumatra.exe runs when you view PDFs with Sumatra PDF Viewer or when Windows opens a PDF with Sumatra by default. It may also stay resident briefly after closing for quick reopen.
Reasons it's running:
- Active PDF Viewing: You're currently viewing a PDF; Sumatra uses a process to render and display pages.
- Default PDF Handler: Windows has Sumatra set as the default PDF viewer, which can launch Sumatra when a PDF is opened from Explorer or another application.
- Background Printing: If you print a PDF, Sumatra may run to handle the print job and render pages for the printer driver.
- Background Tasks: Sumatra may run briefly for tasks like search indexing or quick navigation features.
- Startup or Tray Behavior: If Sumatra is configured to start on login or minimize to tray, you may see Sumatra running after logon or when closing the window.
Can I Disable or Remove sumatra.exe?
Yes, you can disable sumatra.exe. It's safe to close Sumatra when not in use, and you can uninstall it or disable startup if you prefer another PDF viewer.
How to Stop sumatra.exe
- Close All PDFs: Close all open PDF documents within Sumatra, then close the application.
- End a Session: Use the tray icon to exit Sumatra or press Alt+F4 to close the window.
- End All Processes: Open Windows Task Manager (Ctrl+Shift+Esc), find SumatraPDF.exe, right-click → End Task
- Disable Startup: Task Manager → Startup tab → Disable SumatraPDF
- Change Default PDF App: Windows Settings → Apps → Default apps → PDF → Choose another viewer
How to Uninstall Sumatra PDF
- ✔ Windows Settings → Apps → Apps & Features → SumatraPDF → Uninstall
- ✔ Control Panel → Programs → Uninstall a program → SumatraPDF → Uninstall
- ✔ If desired, reboot and install a different PDF viewer of your choice
Common Problems: High CPU or Memory Usage
If sumatra.exe is consuming unusual resources:
Common Causes & Solutions
- Too Many PDFs Open: Close unused PDFs or use the single-window mode to manage documents efficiently.
- Large or Complex PDFs: Large documents may require more memory; try splitting the file or using a lighter rendering mode.
- Outdated Sumatra Version: Update SumatraPDF to the latest version from the official site.
- Corrupted Settings: Reset preferences by renaming the settings file in AppData and restarting Sumatra.
- Printer or Print Driver Issues: Update printer drivers and test printing with another PDF viewer to isolate the issue.
- GPU/Hardware Acceleration: Disable hardware acceleration in Sumatra settings if available or update graphics drivers.
Quick Fixes:
1. Close all unnecessary PDFs with Sumatra open
2. Update to the latest SumatraPDF version
3. Restart SumatraPDF
4. Reset settings if issues persist
5. Check printer drivers and try a different PDF viewer
Frequently Asked Questions
Is sumatra.exe a virus?
No, the legitimate sumatra.exe from SumatraPDF Project is not a virus. Verify the file path is C:\Program Files\SumatraPDF\SumatraPDF.exe or C:\Program Files (x86)\SumatraPDF\SumatraPDF.exe and that the digital signature shows SumatraPDF Project.
Why is sumatra.exe using so much CPU?
High CPU can occur with very large or complex PDFs, heavy rendering, or when multiple documents are open. Try closing extra PDFs, updating Sumatra, or disabling features that render in real-time.
Can I delete sumatra.exe?
Yes, you can uninstall Sumatra PDF via Settings → Apps or Control Panel. Your bookmarks and last documents may be removed unless you back up settings beforehand.
Can I disable sumatra.exe?
Yes, you can close Sumatra when not in use. To prevent startup, disable it in Task Manager → Startup. You can also change the default PDF app to another viewer.
Why does Sumatra PDF start automatically at login?
Sumatra may be configured to start on Windows login or to minimize to the system tray. Disable the startup entry in Task Manager to stop this behavior.
How do I update Sumatra PDF?
Open Sumatra, go to Help or Settings, and choose Check for updates. If an update option isn’t present, download the latest installer from the official SumatraPDF site and install over the existing version.