Upcoming Changes (Ratings, Ranks, and Moderators) (3 July 2026)
Posted: Fri Jul 03, 2026 7:11 pm
The departure of the fastest solvers tables due to the data becoming increasingly polluted with cheats and members using genAI has meant more than just their removal from public view. It has also meant that one of the primary metrics we have used to rate problem difficulties has become increasingly unreliable. In an attempt to find a long term solution to this we have investigated other candidates, and we believe that we have found a balanced hybrid system that should provide measures that are less volatile and in theory can be used with confidence for many years.
Consequently, Project Euler will be taken offline briefly on Saturday to update the site with the new rating system. As mentioned, the previous metric relied heavily on the fastest solvers data, but with extensive correlation analysis it became clear that the fastest solvers data had a definite bias for certain types of problems. Fortunately, all of the new metrics we will be using: dynamic rating, demographic solves, and team ratings, generally agree with each other, which grants a greater degree of confidence in their combined reliability. However, we ask you to prepare for some surprising and, in some cases, seismic shifts in either direction. You will see some previously hard rated problems move down and at the same time other problems will shoot up towards the top.
We appreciate that this might be frustrating for those of you who had been working on that elusive problem at a particular difficulty level. So, ideally we do not want to make any significant changes after this, but there does remain scope to make small calibrations if necessary.
In addition to this, we have also decided to change the number of members at each rank to allow more to feel included. Moving from squares to cubes, we will have 100 Spheres, 800 Icosahedrons, 2700 Dodecahedrons, 6400 Octahedrons, 12500 Cubes, and 21600 Tetrahedrons, which means that 44100 members in total would have a ranked status.
After this update you will also notice below each problem that the information for each problem contains a lot more data. It will show a mean completion time of the most skilled solvers along with some fascinating demographic data, showing the percentage of members at each rank who have successfully solved the problem.
We would also like to thank Icy, griff, and Pacôme for joining a new moderator team. They are well known and respected members in the Project Euler Discord community. Their roles will include helping to keep the discussion threads up to the same high standards we have come to expect, including the removal of posts that disregard our genAI policy. They will also have the capability of viewing profiles of members flagged with suspicious solve patterns and taking action where necessary to help protect the integrity of the vast majority of our members, whilst ensuring that "cheats rarely prosper".
Finally, once we have completed this update and dealt with any bugs, we will be earnestly moving into the next major phase. We can't go into too much detail at this stage, but currently we are planning to introduce private and custom "groups" to Project Euler which will allow like-minded members to track each others progress. We are very excited by this and we hope you share our enthusiasm.
Consequently, Project Euler will be taken offline briefly on Saturday to update the site with the new rating system. As mentioned, the previous metric relied heavily on the fastest solvers data, but with extensive correlation analysis it became clear that the fastest solvers data had a definite bias for certain types of problems. Fortunately, all of the new metrics we will be using: dynamic rating, demographic solves, and team ratings, generally agree with each other, which grants a greater degree of confidence in their combined reliability. However, we ask you to prepare for some surprising and, in some cases, seismic shifts in either direction. You will see some previously hard rated problems move down and at the same time other problems will shoot up towards the top.
We appreciate that this might be frustrating for those of you who had been working on that elusive problem at a particular difficulty level. So, ideally we do not want to make any significant changes after this, but there does remain scope to make small calibrations if necessary.
In addition to this, we have also decided to change the number of members at each rank to allow more to feel included. Moving from squares to cubes, we will have 100 Spheres, 800 Icosahedrons, 2700 Dodecahedrons, 6400 Octahedrons, 12500 Cubes, and 21600 Tetrahedrons, which means that 44100 members in total would have a ranked status.
After this update you will also notice below each problem that the information for each problem contains a lot more data. It will show a mean completion time of the most skilled solvers along with some fascinating demographic data, showing the percentage of members at each rank who have successfully solved the problem.
We would also like to thank Icy, griff, and Pacôme for joining a new moderator team. They are well known and respected members in the Project Euler Discord community. Their roles will include helping to keep the discussion threads up to the same high standards we have come to expect, including the removal of posts that disregard our genAI policy. They will also have the capability of viewing profiles of members flagged with suspicious solve patterns and taking action where necessary to help protect the integrity of the vast majority of our members, whilst ensuring that "cheats rarely prosper".
Finally, once we have completed this update and dealt with any bugs, we will be earnestly moving into the next major phase. We can't go into too much detail at this stage, but currently we are planning to introduce private and custom "groups" to Project Euler which will allow like-minded members to track each others progress. We are very excited by this and we hope you share our enthusiasm.