Who this level is for
Hard Sudoku is for confident solvers who can manage candidates across several units at once.
SudokuIQ puzzle
Play Hard Sudoku online
Solve a free hard Sudoku with notes, smart hints, coaching and local progress. Each board is generated from a valid solved grid and checked for a unique solution.
Logic you will use
Naked pairs, locked candidates, box-line interactions and multi-step elimination become more important.
How to practise
Before placing a digit, identify the row, column or box restriction that proves it. This prevents a plausible guess from damaging later logic.
Do Hard puzzles require guessing?
No. SudokuIQ puzzles are intended to be solved logically; candidate eliminations may need several steps before a placement becomes forced.
What should I learn before Hard Sudoku?
Be comfortable with singles and scanning, then study Naked Pairs and box-line interactions.