Prime95 is a stress-testing and benchmarking tool used to find Mersenne prime numbers. It's popular for testing CPU stability under heavy load, especially in overclocking.
Publisher’s description
What is Prime95?
Prime95 by Mersenne Research, Inc. is proprietary Windows software.
Installation and requirements
The publisher provides Portable installers for 64-bit and 32-bit Windows. The main installer is 8.8 MB. It runs without installation (portable).
Pros / Cons
Pros
- Portable: runs without installation
- Small download (8.8 MB)
Cons
- Proprietary licence: check the terms and price
- No native ARM64 build
- No update for more than a year
In short: Prime95 is a Windows tool for 64-bit and 32-bit PCs. Updates have slowed down.
Is Prime95 safe to download?
- The file is served by download.mersenne.ca; check that it is the publisher’s official mirror
- The download link uses HTTPS
- A SHA256 hash is published, so you can verify the file:
D9475F2FF3F4A6A701ABC49A86A66126CB48ABD10BDA6FA87039D98FA8756BCA· Open the VirusTotal report for this hash - The link answered when we last checked it (October 22, 2026)
- ExeAtlas does not host, wrap or modify installers
Related guide: How to check a file’s SHA256 hash on Windows
Recent versions
All 1 versions ›| Version | Date | Size | Files |
|---|---|---|---|
| 30.19b20Latest | April 25, 2025 | 8.8 MB | 64-bit ZIP32-bit ZIP |
Install from the command line
Silent install ›winget install --id mersenne.prime95 -eRelated guide: How to use winget: install and update apps
Information
- Publisher
- Mersenne Research, Inc.
- Licence
- GIMPS free software license
- Price
- See the publisher’s site
- Requires
- Windows 11 / 10
- Architecture
- 64-bit, 32-bit
- Installer
- Portable
- Version
- 30.19b20
- Released
- April 25, 2025
- Added to the catalogue
- April 25, 2025
- Versions listed
- 1
- winget ID
- mersenne.prime95
Ratings and reviews
No reviews yet. Be the first to rate it.
Frequently asked questions
Is Prime95 free?
Prime95 is proprietary (closed-source) software (licence: GIMPS free software license). Whether it costs money depends on the edition: check the publisher’s site for prices and free tiers.
Is Prime95 safe to download?
The download comes from download.mersenne.ca; ExeAtlas does not host or change the file. Compare its SHA256 hash with the one shown here, or open the VirusTotal report for that hash.
How do I install Prime95 with winget?
Open PowerShell or Windows Terminal and run the winget command shown on this page. winget downloads the official installer and checks its SHA256 hash before running it.
Does Prime95 run on ARM (Windows on Arm)?
There is no ARM64 build; Windows 11 on Arm can run the 64-bit and 32-bit version through emulation.
Can I use Prime95 without administrator rights?
Yes, it is portable: unpack and run it.