Difficulty ratings of classic sudoku from different sources can vary widely, making it hard to know what to expect. We have tried to align our classifications with commonly accepted standards, but there is no one 'right' system. To make it easier for you to find what you're looking for, in addition to our free samples we provide here clear guidance on our classifications so that players who are familiar with the different techniques can identify the levels that match what they're looking for

We currently do not publish any books above Hard level but we're developing new books all the time. If you're looking for harder books or different difficulty ranges you can let us know in our feedback forms and we will expand our range based on requests.

Ratings table

The techniques in each level are cumulative, so each level may contain all the techniques from lower levels in addition to the new techniques at that level. Just because a technique is not listed at a certain level doesn't mean that technique might not still be useful in some puzzles - it just means there is technically a solution path that doesn't require it. Everyone solves differently and that's part of the fun.

Note that the number of givens is often less important than you might think! Within the beginner/easy levels, the required techniques are mainly the same and the difference comes from the number of givens. However, from Medium I and above, difficulty is mainly determined by the techniques needed and the way they are sequenced in the puzzle, so the number of givens tend to fall in the same ranges.