English
▼
0
Mode: Easy
Error: 0/3
Time: 00:00
Classic Sudoku
0
Mode: Easy
Error: 0/3
Time: 00:00
How to Play Sudoku
Basic Sudoku Rules
Sudoku is played on a 9×9 grid split into nine 3×3 boxes. Fill every row, every column, and every box with the digits 1 to 9 — no repeats. Every puzzle has exactly one solution, and you never need to guess: pure logic will get you there. Start with the rows that already have the most given numbers.
Sudoku Encyclopedia
Sudoku took its modern form in the 1970s and conquered the world through Japan in the 1980s. Part logic puzzle, part mental workout, it trains concentration, pattern recognition, and deductive reasoning. Dig into the history, terminology, and mathematics behind the world's favorite number puzzle.
Explore modes
Type Details Sudoku Types
Classic Sudoku
The original 9×9 puzzle and the most-played version in the world. Simple rules, endless depth — every grid has a unique solution that pure logic can unlock, across six difficulty levels from beginner-friendly to extreme.
Daily Sudoku
One fresh puzzle every day, the same for everyone around the world. Keep your streak alive, track your progress on the monthly calendar, and make Sudoku100 part of your daily routine.
Sudoku Battle
Play the classic game head-to-head against real opponents worldwide. Same puzzle, same start — fewer mistakes and faster finishes win the match. Climb the global leaderboard with every victory.
Samurai Sudoku
Five overlapping 9×9 grids forming a giant samurai star. The shared boxes link every grid together, so each solved section unlocks clues for the next. Our most ambitious challenge for seasoned players.
Killer Sudoku
No given numbers at all — just cage sums. Combine classic Sudoku rules with arithmetic deduction to work out where every digit belongs. A favorite of logic purists and math lovers.
Irregular Sudoku
Also known as Jigsaw Sudoku: the 3×3 boxes are replaced by irregularly shaped regions. Rows, columns, and jigsaw regions must still hold 1 to 9. A fresh twist that rewires the way you scan the grid.
Find your level
Six Difficulty Levels, One Smooth Learning Curve
Start with friendly 4×4 mini grids and work your way up to extreme 9×9 puzzles that test even veterans. Every level serves unique-solution puzzles you can solve with logic alone.
Beginner Sudoku
Beginner Sudoku uses a friendly 4×4 mini grid with numbers 1–4 — perfect for kids and first-time players. Four 2×2 boxes and plenty of given numbers mean most puzzles can be solved in a few minutes through simple observation, teaching the core rule: each row, column, and 2×2 box must contain 1 to 4 exactly once.
Avg. time: 2–5 minutes Hints: Use 0–1 hints Givens: 8–10 given numbers
Play now → Easy Sudoku
Easy-level Classic Sudoku is perfect for players who have grasped the basics and want to build confidence. With around 35–40 given numbers, most cells can be solved using Naked Singles and basic elimination. Pencil marks are optional — you can usually solve by direct observation. This is the ideal level to practice before moving on to more challenging puzzles.
Avg. time: 5–10 minutes Hints: Use 0–1 hints Givens: 35–40 given numbers
Play now → Medium Sudoku
Medium-level Classic Sudoku requires systematic logical reasoning. You'll encounter 30–35 given numbers, and solving demands techniques like Hidden Singles, Block Elimination, and candidate management. Pencil marks become essential here — tracking candidates for each cell helps you spot patterns and eliminate impossibilities step by step.
Avg. time: 10–20 minutes Hints: Use 1–2 hints Givens: 30–35 given numbers
Play now → Hard Sudoku
Hard-level Classic Sudoku challenges experienced solvers with deep logic. Only 25–30 numbers are given, and you'll need techniques like Naked Pairs, Hidden Pairs, and Pointing Pairs to make progress. Every deduction requires careful candidate analysis — rushing leads to mistakes. This is where the real puzzle-solving satisfaction begins.
Avg. time: 15–30 minutes Hints: Use 2–3 hints Givens: 25–30 given numbers
Play now → Expert Sudoku
Expert-level Classic Sudoku is reserved for advanced players seeking a true challenge. With only 22–26 given numbers, these puzzles require mastery of advanced techniques like X-Wing, Swordfish, XY-Chain, and forcing chains. Each puzzle is a battle of wits — you must plan multiple steps ahead and consider complex number interactions across the entire board.
Avg. time: 20–45 minutes Hints: Use hints sparingly Givens: 22–26 given numbers
Play now → Extreme Sudoku
Extreme-level Classic Sudoku is the ultimate summit for master players. With the bare minimum of given numbers, every cell demands profound deduction. Techniques like Jellyfish, Coloring, Almost Locked Sets, and nested chains are not luxuries — they're necessities. Only a tiny fraction of solvers can consistently complete extreme puzzles. Are you one of them?
Avg. time: 30–90 minutes Hints: True masters need no hints Givens: 20–24 given numbers
Play now → Latest reads
Blog List Sudoku Blog
Free Sudoku Printing: Why are more and more people falling in love with paper Sudoku again?
Printable Sudoku is more than just "printing out Sudoku puzzles." In this article, we detail why more and more people are rediscovering the joy of paper Sudoku, and the unique advantages paper Sudoku offers over online Sudoku in terms of focus, immersion, and logical reasoning experience. We also delve into the core features of Sudoku100 Printable Sudoku, including: Classic Sudoku, Killer Sudoku, Samurai Sudoku, 12×12 Sudoku, and 16×16 Sudoku. Furthermore, it features a multi-difficulty system, PDF printing of solutions, AI Solver explanations, and logical instruction. Whether you're a Sudoku beginner or an advanced logic puzzle player, Sudoku100 allows you to generate and print your own Sudoku puzzles for free.
Sudoku and Brain Training: Cognitive Benefits Revealed by Scientific Research
Citing the latest research from the United States, the United Kingdom, Iran, and other countries, this article provides an in-depth analysis of how Sudoku can improve BDNF (Brazilian, Brain, and Non-Functional Neuromuscular Development), activate brain functional areas, and delay cognitive aging. Scientific training suggestions are included to help you exercise your brain effectively.
Why Sudoku100
Everything You Need to Play, Learn, and Compete
A complete Sudoku platform built for daily players and serious solvers alike — free, fast, and free of clutter.
100% Free, No Signup
Play unlimited puzzles in your browser with no account required and no paywalls blocking your game.
6 Sudoku Variants
Classic, Daily, Killer, Samurai, 12×12, and 16×16 — plus real-time battles against players worldwide.
Global Battles
Race a real opponent on the same puzzle. Fewer mistakes and faster finishes climb the world leaderboard.
AI Sudoku Solver
Upload a photo of any paper puzzle and get the solution with clear, step-by-step explanations.
Daily Challenge
One curated puzzle every day, with streak tracking and a monthly calendar to keep your habit alive.
Print & Export
Generate printable PDF puzzle books in any type and difficulty — perfect for commutes and classrooms.
Free Open API
Embed unlimited Sudoku puzzles and images on your own site with our free public API.
New to Sudoku?
Start Here in Four Steps
1
Pick a difficulty
Beginner puzzles use a friendly 4×4 mini grid — you only need the basic rules to finish one.
Play Beginner → 2Learn the rules
A 5-minute guide to rows, columns, boxes, and the scanning techniques beginners rely on.
Read the guide → 3Master key strategies
From hidden singles to X-Wing — the techniques that take you from easy to extreme.
Learn strategies → 4Challenge the world
Take your skills into real-time battles against players from around the globe.
Enter a battle →Frequently Asked Questions
View all FAQsIs Sudoku100 free to play?
Yes. Every puzzle, every difficulty, and every game mode on Sudoku100 is completely free. You can play unlimited Sudoku in your browser without creating an account, and there are no paywalls interrupting your game.
Do I need to register an account?
No. You can play, use hints, and track your daily streak without signing up. An optional free account lets you sync statistics, achievements, and battle history across devices.
How do I choose the right difficulty?
If you are new, start with Beginner — those puzzles begin with 40+ given numbers and need only basic scanning. Move up through Easy and Medium as you learn techniques like naked singles and hidden pairs, then take on Hard, Expert, and Extreme.
Are the puzzles guaranteed to have one solution?
Yes. Every puzzle generated on Sudoku100 has exactly one valid solution, and every one can be solved with logic alone — no guessing required.
Can I play Sudoku on my phone?
Absolutely. Sudoku100 is fully responsive and works in any modern mobile browser, with touch-friendly controls, pencil marks, and automatic saving of your progress.
