SumatraPDF.exe

Sumatra PDF Reader

Application ProcessSafePDF Viewer

CPU Usage

1-5%

Memory

20-120 MB

Location

C:\Program Files\SumatraPDF

Publisher

SumatraPDF Team

Quick Answer

sumatra-pdf.exe is safe. It's the official Sumatra PDF Reader executable; it uses a lightweight, single-process design to view PDFs and other formats.

Is it a Virus?

✔ NO - Safe

Must be in C:\Program Files\SumatraPDF\SumatraPDF.exe or C:\Program Files (x86)\SumatraPDF\SumatraPDF.exe

Warning

Often a single process

Multiple tasks may appear if it renders many pages or handles complex PDFs.

Can I Disable?

✔ YES

Close SumatraPDF when not in use; disable startup items if configured

What is SumatraPDF.exe?

sumatra-pdf.exe is the executable for Sumatra PDF Reader, a lightweight, open-source PDF viewer for Windows. It supports PDFs and additional formats, with a minimal UI and fast startup, designed to be portable and resource-efficient.

SumatraPDF uses a straightforward, mostly single-process model with efficient rendering via a lightweight engine. It emphasizes speed and simplicity, with optional plugins and a focus on reliability across Windows versions.

Quick Fact: Sumatra PDF aims for minimal resource usage and fast startup, making it popular on older hardware and lightweight systems.

Types of Sumatra Processes

Main Process: UI and document loading/control (1 instance)
Rendering Subsystem: Page rendering handled within the main process (multi-threaded)
Background Job: Update checks or recent file indexing (optional)

Is sumatra-pdf.exe Safe?

Yes, sumatra-pdf.exe is safe when it's the legitimate file from the official Sumatra PDF project downloaded from sumatrapdfreader.org or official Windows distribution.

Is sumatra-pdf.exe a Virus or Malware?

The real sumatra-pdf.exe is NOT a virus. Malware may imitate names; always verify the file path and signature.

How to Tell if sumatra-pdf.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 other location is suspicious.
Digital Signature: Right-click SumatraPDF.exe Properties Digital Signatures. Should show a valid signer like "SumatraPDF Team" or "SumatraPDF".
Resource Usage: Normal usage is 1-5% CPU per process, 20-120 MB memory. Constant high usage when closed is suspicious.
Behavior: SumatraPDF should run when you open the application and not continuously in the background when you haven't launched it.

Red Flags: If sumatra-pdf.exe is located in unusual folders (Temp, AppData), runs when you haven't opened Sumatra, lacks a signature, or uses constant high resources, scan with antivirus. Be wary of similarly-named files like 'sumatra32.exe' or 'sumatrapdf.exe.bak'.

Why Is sumatra-pdf.exe Running on My PC?

sumatra-pdf.exe runs when you start Sumatra PDF Reader or if it is configured to stay resident for quick reopen. It can also run background tasks for updates or file indexing.

Reasons it's running:

Active Document Viewing: You opened Sumatra PDF with a document; rendering occurs as you navigate pages.
Background Tasks: Update checks, recent-files indexing, or thumbnail generation may run in the background.
Startup Entry: Sumatra PDF may be configured to start with Windows for quick access.
File Association: Opening a PDF from Explorer may launch Sumatra PDF to handle the file.
Thumbnail Previews: System thumbnails or internal previews may involve the Sumatra process.

Can I Disable or Remove sumatra-pdf.exe?

Yes, you can disable sumatra-pdf.exe. It's safe to close Sumatra PDF when not in use, and you can uninstall Sumatra PDF completely if you prefer a different viewer.

How to Stop sumatra-pdf.exe

Close Document: Close all open PDFs via the UI; use File → Exit to shut down the application.
End Task: Open Windows Task Manager, locate SumatraPDF.exe, right-click End Task.
Disable Startup: Task Manager → Startup tab → disable SumatraPDF
Disable Background Tasks: In Sumatra PDF settings, disable update checks or background indexing if available.

How to Uninstall Sumatra PDF

✔ Windows Settings → Apps → Apps & Features → Sumatra PDF → Uninstall
✔ Control Panel → Programs → Uninstall a program → Sumatra PDF → Uninstall
✔ After uninstall, consider an alternative viewer: Adobe Reader, Foxit, or PDF-XChange

Common Problems: High CPU or Memory Usage

If sumatra-pdf.exe is consuming excessive resources:

Common Causes & Solutions

Large or Complex PDFs: Some PDFs with many images or vector graphics can spike CPU. Close the document or split into smaller files.
Background Indexing: Disable or limit thumbnail and index generation in preferences.
Outdated Version: Update Sumatra PDF to the latest release from the official site.
Third-Party Plugins: Disable any plugins or external viewer integrations.
Memory Fragmentation: Restart Sumatra PDF or reboot the system to reclaim memory.
Corrupted PDF Rendering: Open the PDF in another viewer to determine if the file is corrupt; if so, replace the file.

Quick Fixes:
1. Close unnecessary PDFs and restart Sumatra PDF
2. Update Sumatra PDF to the latest version
3. Disable backgrounds tasks in settings
4. Limit open PDFs to reduce memory
5. Run a virus scan to rule out malware

Frequently Asked Questions

Is sumatra-pdf.exe a virus?

No, the legitimate sumatra-pdf.exe from the Sumatra PDF project is not a virus. Ensure the file path is C:\Program Files\SumatraPDF\SumatraPDF.exe or C:\Program Files (x86)\SumatraPDF\SumatraPDF.exe and that the digital signature matches the SumatraPDF Team.

Why is sumatra-pdf.exe using CPU?

PDF rendering can be CPU-intensive for large or image-heavy files. Close unneeded documents, ensure you're using the latest Sumatra PDF, and check for background tasks or thumbnail generation.

Can I delete sumatra-pdf.exe?

Yes, you can uninstall Sumatra PDF through Windows Settings or Control Panel. Your PDFs remain on disk, but you won't be able to view them until you reinstall a viewer.

Can I disable sumatra-pdf.exe?

Yes, you can close Sumatra PDF or disable startup entries in Task Manager. You can also disable background update checks if available.

How do I update Sumatra PDF?

Open Sumatra PDF, go to Help → Check for Updates (or visit sumatrapdfreader.org to download the latest installer) and install the update.

Why are there many processes when I open a PDF?

Sumatra PDF typically runs as a single process with rendering inside it, but some actions like thumbnail generation or Windows Explorer previews can trigger additional background threads or processes temporarily.