Sudoku Difficulty Explained
What actually changes between easy, medium, hard, and expert puzzles.
Difficulty is not about grid size — it is about which solving techniques you need.
All sudoku puzzles use the same 9×9 grid and the same rules. What changes between easy and expert is the set of solving techniques you need to reach the unique solution.
Part of: Daily Challenges
Quick answer
Difficulty is not about grid size — it is about which solving techniques you need.
Key points
- ▸ Easy: 35+ given digits. Solvable with naked singles and hidden singles only.
- ▸ Medium: 28–32 givens. Requires naked pairs, pointing pairs, box-line reduction.
- ▸ Hard: 25–28 givens. Adds X-wing, swordfish, chains.
- ▸ Expert: 22–25 givens. Requires advanced techniques like XY-wing, uniqueness rectangles, possibly guessing.
- ▸ Minimum givens for a unique puzzle = 17. These are expert-only.
Examples
- Easy puzzleYou can fill in digits just by scanning rows, columns, and boxes for "only one place this can go".
- MediumScanning alone gets you stuck. You need to note candidates and spot pairs like "these two cells can only be 3 or 7".
- ExpertPencil marks everywhere. Progress requires spotting complex patterns — X-wings, chains, or in some cases trial-and-error.
When to use which tool
- Easy SudokuStart here if you are new. 35+ givens, solvable with scanning only.Play easy Sudoku in your browser. About 36 given clues — ideal for beginners or a quick puzzle.
- Medium SudokuNext step up — requires candidate notation.Play medium Sudoku in your browser. About 30 clues — needs light scanning and candidate elimination.
- Hard SudokuIntroduces X-wing and related intermediate techniques.Play hard Sudoku in your browser. Around 26 clues — requires chains, pairs, and patient elimination.
- Expert SudokuTop difficulty — advanced techniques required.The toughest Sudoku. ~22 clues — requires advanced techniques and patience.
Related
- SudokuPlay Sudoku in your browser. Easy, medium, hard, and expert boards. Auto-save progress.
- Easy SudokuPlay easy Sudoku in your browser. About 36 given clues — ideal for beginners or a quick puzzle.
- Medium SudokuPlay medium Sudoku in your browser. About 30 clues — needs light scanning and candidate elimination.
- Hard SudokuPlay hard Sudoku in your browser. Around 26 clues — requires chains, pairs, and patient elimination.
- Expert SudokuThe toughest Sudoku. ~22 clues — requires advanced techniques and patience.
- Beginner Sudoku StrategyNaked singles and hidden singles — most easy puzzles need nothing else.
Frequently asked questions
› Do fewer givens always mean harder?
Usually, but not always. A puzzle with 30 givens requiring an X-wing is harder than one with 26 givens solvable by hidden singles. Technique matters more than count.
› Can an expert-level puzzle always be solved without guessing? Trust & accuracy
In principle yes, but the technique required may be obscure enough that guess-and-check is faster in practice. The "true" difficulty of a puzzle is the minimum-technique set needed.
› How should I use this guide with a Kefiw tool? How-to
Use the guide as the plan and the linked Kefiw tool as the check. Read the steps first, try the move manually, then use the tool to compare outputs, catch edge cases, and decide whether the result actually fits your task.
› What mistake do tool guides help avoid? Troubleshooting
Tool guides help avoid using a utility mechanically without understanding what you are trying to accomplish. Most word, writing, and text utilities are fast, but speed can hide context mistakes. Know whether you are solving a puzzle, cleaning copy, drafting a line, or checking a rule.
› Can a tool guide help me learn the skill? How-to
A tool guide can help you learn if you pause before accepting the output and ask why it worked. Compare your first guess with the tool result, look for the rule or pattern, and repeat that review. Passive copying solves one task; active review builds the skill.