Play Sudoku Online for Free
Sudokupulse gives you unlimited free Sudoku puzzles across six difficulty levels — from gentle introductions to fiendishly difficult grids. No registration, no ads interrupting your flow, and every feature you need to improve as a solver.
- Six difficulty levels — Progress from easy through medium, hard, expert, and evil as your skills grow, or try a new daily puzzle every day.
- Smart solving tools — Use candidate mode, notes, undo, and hints to develop your technique without frustration.
- Works everywhere — Play on your phone, tablet, or desktop with a responsive interface built for touch and keyboard.
- No account needed — Start playing instantly. Your progress is saved automatically in your browser.
How to Play Sudoku
Sudoku is a logic-based number puzzle played on a 9×9 grid divided into nine 3×3 boxes. The goal is simple: fill every row, column, and box with the numbers 1 through 9 so that no number repeats. No math is involved — Sudoku is purely a game of deduction and pattern recognition.
Here’s how to get started:
- Look for cells with limited options. Start with rows, columns, or boxes that already have many numbers filled in. The fewer empty cells remain, the easier it is to determine which numbers are missing.
- Use the process of elimination. For each empty cell, check which numbers already appear in its row, column, and box. If only one possibility remains, that’s the answer — this is called a naked single.
- Mark candidates. When a cell has two or three possibilities, use pencil marks (notes) to track them. Sudokupulse’s candidate mode makes this easy — just toggle it on and tap numbers to add or remove candidates.
- Scan for hidden singles. Sometimes a number can only go in one cell within a row, column, or box, even if that cell has multiple candidates. Learning to spot hidden singles is one of the most important beginner skills.
- Work through the grid systematically. Move between rows, columns, and boxes rather than staring at one spot. Fresh perspectives often reveal placements you missed.
For a complete walkthrough, read our guide on how to play Sudoku or review the full Sudoku rules.
Choose Your Difficulty Level
Sudokupulse offers six distinct difficulty levels, each requiring progressively more advanced solving techniques:
| Level | Starting Clues | Techniques Needed | Best For |
|---|---|---|---|
| Easy | 36–45 | Naked singles, hidden singles | Beginners learning the basics |
| Medium | 30–35 | Naked pairs, hidden pairs, pointing pairs | Players ready for more challenge |
| Hard | 26–30 | Pointing pairs, box-line reduction, naked triples | Experienced solvers |
| Expert | 22–26 | X-Wing, Swordfish, XY-Wing | Advanced players |
| Evil | 17–22 | Chains, coloring, multi-step eliminations | Elite solvers |
| Daily | Varies | Mixed | Everyone — a fresh puzzle each day |
Not sure where to start? Begin with easy puzzles and work your way up. Most players find that medium is the sweet spot where Sudoku starts to feel genuinely exciting.
Beginner Tips
If you’re new to Sudoku, these fundamentals will accelerate your learning:
- Start with easy puzzles to build pattern recognition before increasing difficulty.
- Learn naked and hidden singles first. These two techniques — naked singles and hidden singles — solve every easy puzzle and remain essential at every level.
- Always use pencil marks. Keeping accurate candidate lists prevents mistakes and reveals patterns you’d otherwise miss.
- Never guess. Every Sudoku puzzle has a unique solution reachable through logic alone. If you’re stuck, look for a technique you haven’t tried yet rather than guessing.
- Scan in both directions. After filling in a number, immediately check what new information that reveals in the intersecting row, column, and box.
For more detailed guidance, read our beginner strategies guide.
Improve Your Solving Skills
Ready to move beyond the basics? Sudokupulse has a complete library of resources:
- Technique guides — Step-by-step explanations of 12 solving techniques, from naked singles to XYZ-Wings.
- Practice puzzles — Curated puzzles designed to exercise specific techniques like pointing pairs or X-Wings.
- Strategy articles — In-depth guides covering beginner strategies, advanced strategies, and topics like the 45 rule.
- Sudoku solver — Paste any puzzle to see the step-by-step solution and verify your work.
Frequently Asked Questions
How many valid Sudoku puzzles exist? There are approximately 6.67 sextillion (6.67 × 10²¹) valid completed Sudoku grids. When you factor in symmetry, there are about 5.47 billion essentially different grids — you’ll never run out of puzzles to solve.
Is Sudoku a math game? No. Despite using numbers, Sudoku is a logic puzzle. You could replace the digits 1–9 with letters, colors, or symbols and the game would work identically. The skill is deduction, not calculation.
What’s the minimum number of clues needed for a unique solution? Research has proven that a Sudoku puzzle needs at least 17 clues to have a unique solution. Our evil puzzles sometimes approach this minimum, making them extremely challenging.
How long should a Sudoku puzzle take? This varies widely by difficulty and experience. Beginners might spend 10–20 minutes on an easy puzzle, while experienced solvers can finish one in under 3 minutes. Hard and evil puzzles can take 30 minutes to over an hour even for skilled players.
Can every Sudoku puzzle be solved without guessing? Yes. Every properly constructed Sudoku puzzle — including all puzzles on Sudokupulse — can be solved through logic alone. If you feel the need to guess, there’s a technique you haven’t applied yet. Check our techniques page for strategies you might be missing.