The hardest Sudoku in the world

Sep 2022

Hardest sudoku ever

In June 2012, Arto Inkala, a Finnish mathematician and sudoku enthusiast, claimed to have designed the worlds hardest sudoku ever created.

Arto's monsterpiece has only one possible solution and it took Arto about 3 months to design it, and we can only hope it will not take as long to solve it.
needless to say, we're too scared to try.

The hardest sudoku puzzle ever created has 23 pre-filled squares from the total of 81 sudoku squares.
In comparison, our Beginner, easy, medium and hard sudokus has 54, 36, 27 and 18 pre-filled squares respectively.

Arto's sudoku puuzle, think you can solve it?
read below

Hardest sudoku ever board

Despite having less pre-filled suares, our Hard sudokus aren't harder than Arto's puzzle since they have more than one solution, which makes them significantly easier to solve than sudoku puzzles that have a single solution.

Want to play the hardest sudoku ever created?

We've created a special, and secret page featuring Arto's unique suokdu design.
Play the hardest sudoku ever created!

Want to learn how Sudoku difficulty is measured?

We have created a short and informative article about how a sudoku puzzle difficulty is measured, Click here to read it.