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Welcome to PrimeGrid[edit | edit source]

PrimeGrid is a distributed computing project which utilizes BOINC and PRPNet to search for primes. The primary goal is to bring the excitement of prime finding to the "everyday" computer user. Simply download the software and let your computer do the rest. Participants can choose from a variety of prime forms to search. With a little patience, you may find a large or even record breaking prime and enter into Chris Caldwell's The Largest Known Primes Database as a Titan!

PrimeGrid's secondary goal is to provide relevant educational materials about primes. Additionally, we wish to contribute to the field of mathematics.

Lastly, primes play a central role in the cryptographic systems which are used for computer security. Through the study of prime numbers it can be shown how much processing is required to crack an encryption algorithm and thus to determine whether current security schemes are sufficiently secure.

The Search for Primes[edit | edit source]

In the search for prime numbers, there are two main areas of participation: sieving and primality testing. Sieving quickly narrows down the search field and what remains is tested for primality.

Sieving - Sieving is the first step to prime finding. In general, a sieve separates wanted from unwanted material using a tool such as a mesh, net or other filtration or distillation methods. The word "sift" derives from this term. In PrimeGrid's case, the desired elements ultimately are prime numbers and the unwanted material are composite numbers. Sieve applications used at PrimeGrid.
Primality Testing - A primality test is conducted on all the candidates remaining from the sieve. PrimeGrid uses several primality programs. The Lucas-Lehmer-Riesel (LLR) test is one such program developed by Jean Penne that tests numbers of the form N = k*2^n-1, with 2^n > k. It includes the Proth test to perform +1 tests and PRP to test non base 2 numbers. Primality applications used at PrimeGrid.

How to Participate[edit | edit source]

Users can participate in PrimeGrid in two ways, through BOINC or through the Project Staging Area (PSA). Before participating, please read PrimeGrid's rules and policies.


The Berkeley Open Infrastructure for Network Computing (BOINC) is a non intrusive application used for distributed computing. It is available for various operating systems, including Linux, Mac OS X, and Microsoft Windows.

  1. Download, install and run the BOINC software used by PrimeGrid.
  2. When prompted, enter the URL:
  3. If you are not using a graphics enabled BOINC client, you may use the manual registration form.
  4. PrimeGrid is only one of many projects that may be run under BOINC.  If you run just one project, PrimeGrid, or many projects, you may want to try an account manager such as GridRepublic or BAM!.  
  5. This concludes instructions for initiating PrimeGrid through the BOINC application.  To manage your Project preferences, including the PrimeGrid Project, use the BOINC application or your selected account manager.
  6. To select and manage PrimeGrid's many Subprojects, access the PrimeGrid preferences page through your PrimeGrid Account. Go to the PrimeGrid home pageto login and access your Account.

Project Staging Area (PSA)

The PSA was originally created to research, test, and prepare future projects for PrimeGrid BOINC. It has since been expanded to offer more varied prime searches that normally will not make it to BOINC. There are two avenues to participate in the PSA - PRPNet and Sieving.

  • PRPNet - PRPNet, developed by Mark Rodenkirch, is very similar to BOINC but is used specifically for prime finding. There is no GUI. Instead, it runs in a dos window or Linux terminal. It's very simple to run...just download and unzip the file for your OS, edit a few lines in the prpclient.ini file, and run. You'll be crunching in less than 5 minutes. :) Instructions for installing and running PRPNet.
  • Manual Sieving - A good sieve leads to a better prime search. While we attempt to do most of the prep work internally, some efforts are so large that we need the assistance of the community. There are several projects being coordinated in the PST forum. For more information, see (not ready yet).

Manual cobblestones are available to be awarded towards the PSA badge.

PrimeGrid Preferences[edit | edit source]

After logging in to your account, you can manage a number aspects of how your computers run the PrimeGrid applications through BOINC. The basics on configuring those preferences are here.

PrimeGrid Subprojects[edit | edit source]

PrimeGrid offers a number of subprojects for finding primes, and for sieving.  Some of these are available through the BOINC client, some of these are available through the PRPNet client, and some are manual, that is, they require manually checking out work units and uploading results.  Different subprojects may run on different operating systems, and may have executables for CPUs, GPUs, or both.  For a list of what projects are available on what hardware and platforms, go here.

BOINC Projects[edit | edit source]

Sieving[edit | edit source]

Proth Prime Search (Sieve)
321 Prime Search (Sieve)

LLR[edit | edit source]

321 Prime Search (LLR)
Cullen Prime Search (LLR)
Fermat Divisor Search (LLR)
Generalized Cullen/Woodall Prime Search (LLR)
Prime Sierpinski Problem (LLR)
Proth Prime Search (LLR)
Sierpinski/Riesel Base 5 Problem (LLR)
Seventeen or Bust (LLR)
Sophie Germain Prime Search (LLR)
The Riesel Problem (LLR)
Woodall Prime Search (LLR)

Other[edit | edit source]

Wieferich Prime Search
Wall-Sun-Sun Prime Search

Generalized Fermat Prime Search (GFN)[edit | edit source]

For b2n+1, n=15-22, 2<b<400M

PSA Projects:[edit | edit source]

PRPNet[edit | edit source]

27 Prime Search
121 Prime Search
Factorial Prime Search
Primorial Prime Search

Manual Sieving[edit | edit source]

Generalized Fermat (Suspended)

Credit, Cobblestones & Badges[edit | edit source]

PrimeGrid awards badges to users in recognition of achieving certain defined levels of credit for work done. The badges are of no intrinsic value but are valued by many as a sign of achievement. The issuing of badges should also benefit PrimeGrid by evening out the participation in the less popular sub projects. The easiest of the badges can often be obtained in less than a day by a single computer, whereas the most challenging badges will require far more time and computing power. You can find a more detailed description here.


Latest activity[edit | edit source]

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