Welcome to Sudoku! If you're completely new to this amazing puzzle, you're in the right place. This guide will teach you everything you need to start playing, with zero prior knowledge required. By the end, you'll be confidently solving your first Sudoku puzzles!
Our Beginner mode features Master Sudo, your friendly guide who teaches you step-by-step. Perfect for your first puzzles!
Try Beginner Mode →Sudoku is a number puzzle played on a 9×9 grid. Your goal is to fill in all the empty squares with numbers 1-9, following three simple rules. That's it! No math required, no tricks—just logic and pattern recognition.
You don't need to be good at math! Despite using numbers, Sudoku requires zero mathematical ability. The numbers could be replaced with letters, colors, or symbols. They're just convenient markers. If you can count to 9, you can play Sudoku!
Every Sudoku puzzle follows these three rules. Master these, and you understand the entire game:
That's all! Every number you place must follow all three rules simultaneously.
The Sudoku grid has three important parts:
Your puzzle starts with some numbers already filled in (called "givens"). These are locked and can't be changed. Your job is to fill the empty cells.
The easiest way to start is by scanning. Here's how:
If a row has 1,2,3,4,5,6,7,8 and one empty cell, that cell must be 9! That's the only number missing from 1-9.
Find rows, columns, or boxes that already have 6-8 numbers. These are the easiest to complete because only 1-3 numbers are missing.
Pick a number (start with 1) and scan the entire grid looking for where 1 can go. Then do the same for 2, 3, etc.
Before placing a number, verify:
For each empty cell, ask: "Which numbers CAN'T go here?" The answer is often simpler than asking which numbers CAN go there.
Each number you place makes the next number easier to find. The puzzle gets simpler as you progress!
No! Every proper Sudoku puzzle can be solved using only logic. If you find yourself guessing, there's a logical step you haven't found yet. Our Beginner mode with Master Sudo will show you the logical steps.
No problem! Our online game has an Undo button. Mistakes are part of learning. When you validate your puzzle, it will show you errors to learn from.
Your first puzzles might take 20-30 minutes, and that's perfectly normal! As you practice, you'll naturally get faster. Don't worry about time—focus on understanding the logic.
For your first few puzzles, try without notes to focus on the basic logic. Once comfortable, notes mode becomes very helpful! Our game has built-in notes—click the pencil icon.
Our online Sudoku has special features perfect for learning:
Start with Beginner mode. Master Sudo will explain every move. Play 2-3 puzzles to understand the basics.
Move to Easy difficulty. Try solving without hints. Use the Validate button to check progress.
Solve 2-3 Easy puzzles daily. Focus on recognizing patterns faster.
You're no longer a complete beginner! Try timing yourself and see how far you've come.
You're ready to move from Easy to Hard when:
Begin with our guided Beginner mode—Master Sudo will teach you everything!
Start Learning Now →The best way to learn sudoku is to walk through a real puzzle together. Let's solve part of an Easy puzzle step by step so you can see exactly how logical thinking works in practice. Once you understand this process, you can try a puzzle on your own.
Imagine you have a 9×9 grid in front of you. Some cells are already filled with numbers (the "givens"), and the rest are blank. An Easy puzzle typically starts with 35-45 givens, leaving you around 36-46 cells to fill. That might sound like a lot, but each placement makes the next one easier.
Your first move should always be to scan the grid for any row, column, or 3×3 box that already has most of its numbers filled in. Suppose you spot a row that reads: 3, _, 7, 1, 9, 5, 8, 2, 6. There is only one empty cell, and the numbers present are 1, 2, 3, 5, 6, 7, 8, 9. The missing number from the set 1-9 is 4. You can confidently write 4 in that blank cell. This is the simplest type of deduction, and Easy puzzles are full of moments like this.
Next, pick a number—let's say 5—and look at the entire grid. Find every row, column, and box that already contains a 5. Now look at the boxes that do NOT yet have a 5. Within each of those boxes, many cells will be eliminated because their row or column already has a 5. Often, only one cell in that box remains as a valid spot. Place the 5 there.
This technique is called cross-hatching, and it is the single most useful method for beginners. You are essentially drawing imaginary lines through the grid from every existing 5, and seeing where those lines leave only one opening.
Let's say you are looking at the top-left 3×3 box. It contains the numbers 2, 6, and 9, leaving six empty cells. That feels like a lot of possibilities, but start checking each empty cell:
Each time you successfully place a number, you add a new constraint that helps solve the remaining cells. This cascading effect is what makes sudoku so satisfying.
After placing several numbers, go back to rows, columns, or boxes where you were stuck earlier. The numbers you just placed may have created new "easy wins." This back-and-forth scanning is the natural rhythm of solving sudoku. You do not work through the grid in order from top-left to bottom-right—you jump to wherever the next logical deduction is clearest.
Continue scanning, cross-hatching, and eliminating. On an Easy puzzle, these basic techniques are enough to fill every cell. You should never need to guess. If you feel stuck, slow down and systematically check every row, column, and box—there is almost always a placement hiding in plain sight. For more structured techniques, see our sudoku tips and tricks page.
Solving sudoku is a cycle: scan → eliminate → place → repeat. You are not doing complex math. You are simply asking, "Which numbers are already taken?" and finding the one that is left. With practice, this process becomes second nature.
Every sudoku player makes mistakes when starting out. Recognizing these pitfalls early will save you frustration and help you build good habits from day one.
This is the most common mistake beginners make. When you feel stuck, it is tempting to think, "Maybe a 3 goes here?" and just try it. The problem is that a wrong guess can ripple through the entire grid, creating contradictions many moves later that are almost impossible to untangle. Every well-constructed sudoku puzzle has exactly one solution, and it can always be reached through pure logic—no guessing required.
What to do instead: If you cannot find a certain placement, move on to a different part of the grid. There is almost always an easier deduction waiting somewhere else. If you are truly stuck, use the hint feature in our online sudoku game to see the logical next step rather than guessing.
A number must satisfy the row, column, and box rule simultaneously. Beginners often check one or two constraints and forget the third. For example, you might confirm that 7 is missing from a row and missing from the column, then place it—only to realize later that the 3×3 box already contains a 7.
What to do instead: Build a mental checklist. Every single time you are about to write a number, ask three questions: Is it in this row? Is it in this column? Is it in this box? Only place the number when all three answers are "no." This takes a few extra seconds but prevents costly errors.
Excitement can lead to sloppy play. You spot what looks like an obvious placement, write it in immediately, and only later discover it was wrong. Speed is not the goal when you are learning—accuracy is.
What to do instead: Slow down deliberately. Double-check each placement. It is far faster to spend five extra seconds verifying a number than to undo a chain of mistakes ten minutes later. As your pattern recognition improves, speed will come naturally.
Some beginners avoid pencil marks (small candidate numbers written in cells) because they seem complicated or messy. However, as puzzles get harder, trying to keep all possibilities in your head becomes impossible. Skipping pencil marks forces you to rely on memory, which leads to errors.
What to do instead: Start using pencil marks once you are comfortable with the basic rules. You do not need them for the simplest Easy puzzles, but they become essential at Medium difficulty and above. Our online game has a built-in notes mode—tap the pencil icon to toggle it on.
Beginners sometimes fixate on one row or one box, trying to complete it fully before moving on. This rarely works because you usually need information from other parts of the grid to make progress.
What to do instead: Keep your focus flexible. Scan the entire grid regularly. When you place a number, immediately check whether it helps solve cells in the same row, column, or box. The best solvers constantly shift their attention across the whole puzzle.
Once you understand the three rules of sudoku, it is time to learn the specific techniques that help you find where numbers go. These three foundational methods will carry you through Easy and Medium puzzles with confidence. For a deeper exploration of advanced strategies, visit our complete sudoku guide.
A naked single occurs when a cell has only one possible number that can go in it. This happens when eight of the nine digits (1-9) are already present in the cell's row, column, or box (combined). The one remaining digit is the answer.
How to find naked singles:
Suppose an empty cell is in a row containing 1, 3, 5, 7, 9—a column containing 2, 4, 5, 8—and a box containing 1, 2, 6. Combining these: 1, 2, 3, 4, 5, 6, 7, 8, 9 are all present except... wait, they are all present? Let's count: {1,2,3,4,5,6,7,8,9}. The only number NOT in that combined set would be the answer. In this case, every digit appears, which means we need to recount carefully (remember, duplicates across row/column/box are normal—we only care about the union). The unique numbers seen are {1,2,3,4,5,6,7,8,9}. If only eight unique numbers appear, the ninth is your answer!
Naked singles are the most straightforward technique in sudoku. On Easy puzzles, you can often solve the entire grid using naked singles alone.
A hidden single is when a particular number can only fit in one cell within a row, column, or box—even though that cell might technically allow other numbers too. The number is "hidden" because the cell has multiple candidates, but within its group, it is the only place that number can go.
How to find hidden singles:
Consider the middle-left 3×3 box. It does not contain a 7 yet. The box has four empty cells. Check each one: the first cell's row already has a 7, the second cell's column already has a 7, and the third cell's row also has a 7. Only the fourth empty cell can accept a 7. Even though that fourth cell might also accept other numbers like 3 or 9, you know the 7 must go there because it has nowhere else to go in this box.
Hidden singles are slightly harder to spot than naked singles because you need to think about a number's options across an entire group rather than a single cell's options. However, they are extremely powerful and appear frequently in every puzzle.
Pencil marks are small numbers written in empty cells to track which values are still possible. Instead of committing to a single large number, you jot down all candidates. As you make placements elsewhere on the grid, you erase candidates that are no longer valid. This technique is also called "candidate notation."
How to use pencil marks effectively:
When to start using pencil marks: For your very first puzzles, try solving without pencil marks to build your scanning skills. Once you move to Medium difficulty or find yourself frequently stuck on Easy puzzles, introduce pencil marks. They transform the puzzle from a memory challenge into a visual one.
In our online sudoku game, pencil marks are built in. Just tap the pencil icon to toggle notes mode, then tap numbers to add or remove candidates from a cell. The game even highlights conflicts automatically.
Sudoku difficulty levels are not arbitrary—they reflect how many and which techniques you need to solve the puzzle. Understanding this progression helps you know when you are ready for the next challenge and what skills to develop.
Easy puzzles are designed to be solvable with naked singles and simple scanning. They have the most givens (typically 36-45 pre-filled cells) and require no advanced techniques. Your goal at this level is to become comfortable with the three rules, develop consistent scanning habits, and build confidence.
You are ready to move on when: You can solve Easy puzzles in under 10-15 minutes without using hints, and they no longer feel challenging.
Medium puzzles have fewer givens (around 30-35) and require you to find hidden singles consistently. You will encounter positions where no naked single exists, and you must think about where a number can go within a row, column, or box. This is where pencil marks start becoming genuinely useful.
New skills needed: Systematic use of pencil marks, hidden single detection, and patience. Medium puzzles take longer not because they are "harder math" but because the logical deductions are less obvious.
You are ready to move on when: You can solve Medium puzzles in under 15-20 minutes and recognize hidden singles without pencil marks for simple cases.
Hard puzzles have even fewer givens (around 25-30) and introduce situations where you need techniques beyond singles. You may encounter naked pairs (two cells in a group that share the same two candidates, eliminating those candidates from other cells), pointing pairs, and other intermediate strategies.
New skills needed: Full pencil marking of the grid, recognizing pairs and triples, and understanding candidate elimination. Our tips and tricks guide covers these techniques in detail.
At the highest levels, puzzles require advanced techniques like X-Wings, Swordfish, XY-Chains, and more. These are not for beginners, but knowing they exist can be motivating. Every expert solver started exactly where you are now.
Here is a realistic timeline for most players:
There is no rush. Many players happily solve Easy or Medium puzzles for years and find great satisfaction in it. The daily sudoku challenge is a wonderful way to maintain a consistent practice habit at whatever difficulty you enjoy.
Most people can understand the rules and solve their first Easy puzzle within 30-60 minutes. Becoming comfortable enough to solve Easy puzzles without help typically takes a few days of practice (3-5 puzzles). Reaching a level where you can tackle Medium puzzles usually takes 2-4 weeks of regular play. The beauty of sudoku is that you are "playing" from the very first puzzle—learning and enjoying happen at the same time.
No! This is one of the biggest misconceptions about sudoku. Despite using numbers 1-9, sudoku involves zero arithmetic. You never add, subtract, multiply, or divide. The numbers are simply symbols used to fill the grid—they could just as easily be letters A through I, nine different colors, or even nine different animal icons. Sudoku is a logic and pattern-recognition puzzle, not a math problem. If you can tell the difference between nine symbols, you can play sudoku.
The easiest standard difficulty is typically called "Easy" (sometimes labeled "Beginner" or "Simple" depending on the app or website). Easy puzzles start with the most pre-filled numbers—usually 36-45 of the 81 cells are already given. This means you only need to fill in 36-45 cells, and the logic required is straightforward. On our site, we also offer a special Beginner mode with Master Sudo, which is even easier than Easy because it provides step-by-step guidance explaining why each number goes where. If you have never played before, start with Beginner mode for the gentlest introduction possible.
For your very first 5-10 puzzles, try solving without pencil marks. This forces you to practice scanning and builds your ability to hold information in your head, which strengthens your solving intuition. Once you feel comfortable with the basic rules and scanning technique, start introducing pencil marks. They become essential at Medium difficulty and above because the puzzles have too many possibilities to track mentally. Think of pencil marks as training wheels in reverse—you start without them to build core skills, then add them to handle greater complexity.
A correct solution has every row, every column, and every 3×3 box containing all digits from 1 through 9 exactly once, with no repeats and no missing numbers. When playing on our site, you can tap the Validate button at any time to check your progress. The game will highlight any cells that conflict with the rules, so you can catch and fix errors early. If you complete the entire grid without conflicts, you have solved the puzzle correctly. A properly designed sudoku puzzle always has exactly one valid solution.
You can absolutely solve sudoku on paper—that is how millions of people have enjoyed the puzzle for decades, in newspapers and puzzle books. However, a digital version like our free online sudoku offers convenient advantages for beginners: automatic error checking, easy undo, built-in pencil marks, hints when you are stuck, and no need for an eraser. Many players enjoy both formats. Paper is great for unplugged relaxation, while digital is ideal for learning because of the instant feedback.
First, take a breath. Getting stuck is normal and happens to everyone, including experienced players. Try these steps in order: (1) Systematically scan every row, column, and box—there is usually a placement you overlooked. (2) Switch to a different number and scan for it across the entire grid. (3) If you are not using pencil marks, try adding them to the area where you are stuck. (4) Use the hint feature in our game to see the next logical step. (5) Take a short break and come back with fresh eyes. Often, a placement that was invisible before will jump out immediately after a break. For more problem-solving strategies, check our sudoku tips and tricks page.
Once you're comfortable with the basics:
Everyone who's now an expert solver was once exactly where you are—a complete beginner staring at a confusing grid. The difference is they practiced and learned. You can too!
Welcome to the wonderful world of Sudoku. Happy puzzling! 🧩
Last Updated: January 2026 | TrySolitaire Home | Play Sudoku