AI SUDOKU
How to Play Sudoku: A Beginner's Guide
Sudoku is the world's most popular logic puzzle, and the best part is that you can learn how to play it in about a minute. There is no maths and no guessing — just a 9×9 grid, the digits 1 to 9, and three simple rules. This guide explains exactly how Sudoku works, how to make your first moves, and the habits that turn a beginner into a confident solver. When you are ready, you can play free Sudoku online right here with an AI Hint button to help you learn.
What Is Sudoku?
Sudoku is a number-placement puzzle played on a square grid of 81 cells, arranged as nine rows, nine columns, and nine smaller 3×3 boxes. Some cells start with numbers already filled in — these are your clues. Your job is to fill in every remaining empty cell using the digits 1 to 9, following three rules:
- Each row must contain the digits 1–9, with no number repeated.
- Each column must contain the digits 1–9, with no number repeated.
- Each 3×3 box must contain the digits 1–9, with no number repeated.
That's the entire game. The numbers don't add up to anything — they're just nine symbols that each have to appear exactly once in every row, column, and box. A properly made puzzle has only one possible solution, and you can always reach it with logic alone.
The Sudoku Grid: Rows, Columns and Boxes
Understanding the three "groups" is the key to everything. Every single cell belongs to exactly one row, one column, and one 3×3 box at the same time. That means whenever you place a number, it instantly affects all three of those groups — a digit you put in a cell rules that digit out of the other eight cells in its row, the other eight in its column, and the other cells in its box.
Good players think in terms of these groups rather than individual cells. Instead of asking "what goes in this cell?", you ask "where can this digit go in this box?" That small shift in perspective is what unlocks the puzzle.
How to Play Sudoku, Step by Step
- Pick a cell. Tap or click any empty cell on the board.
- Enter a digit. Choose a number from the on-screen pad, or just type 1–9 on your keyboard. Use Backspace (or the Erase button) to clear a cell.
- Check the three rules. Before committing, make sure that digit doesn't already appear in the same row, column, or 3×3 box. If it does, it's not allowed there.
- Use pencil marks when it gets tricky. Switch to Candidate mode to jot the small "maybe" numbers a cell could hold. These notes are the foundation of every advanced technique.
- Keep going until the grid is full. Each correct number you place narrows down the others, so the puzzle gets easier as you progress.
💡 Tip: Stuck on a move? Press the AI Hint button. It finds the next logical step and names the technique, so you learn the pattern instead of just getting the answer.
Your First Moves: Where to Start
Don't start by staring at an empty cell — start by looking for the easiest wins:
1. Find the "almost full" groups
Scan for any row, column, or box that already has eight of its nine numbers. The missing digit is forced — there's only one place it can go. Fill all of these in first; they're free.
2. Hunt one digit at a time
Pick a number, say 7. Look at each 3×3 box that doesn't have a 7 yet. Within that box, cross out every cell that already "sees" a 7 in its row or column. If only one cell survives, that's where the 7 goes. Sweep all nine boxes for that digit, then move to the next.
These two techniques alone will completely solve most easy puzzles and get you a long way into medium ones.
Common Beginner Mistakes
- Guessing. Sudoku never requires it. If you find yourself guessing, there's a logical move you've missed — look again.
- Ignoring boxes. Beginners watch rows and columns but forget the 3×3 box rule, which is often where the decisive clue lives.
- Skipping pencil marks. Trying to hold every possibility in your head on a hard puzzle leads to errors. Write candidates down.
- Forgetting to re-scan. Every number you place can unlock new forced moves elsewhere — recheck the affected row, column, and box after each placement.
Tips to Get Better
Once the rules feel natural, progress comes from playing regularly and learning to read the board faster. Start on Easy to build confidence, then move to Medium and Hard as the simple scans stop being enough. When a puzzle stalls, that's your cue to learn a new technique rather than guess. Our Sudoku strategy guide covers the next steps — hidden singles, naked pairs, pointing pairs and the X-Wing — and the Sudoku blog explains how puzzles are generated and solved behind the scenes.
Frequently Asked Questions
How do you play Sudoku for beginners?
Sudoku is played on a 9×9 grid split into nine 3×3 boxes. Your goal is to fill every empty cell so that each row, each column, and each 3×3 box contains the digits 1 to 9 exactly once — no repeats anywhere in a row, a column, or a box. You start with some numbers already placed; those clues can never be changed. As a beginner, look for rows, columns, or boxes that are almost full: if eight of the nine cells are filled, the ninth is forced. Then pick a single digit and scan the grid to see which box still needs it and where it can legally go. Work only from numbers you can prove — Sudoku never requires guessing. Every well-made puzzle has exactly one solution reachable by pure logic.
What are the rules of Sudoku?
Sudoku has just three rules. First, each of the nine rows must contain the digits 1 through 9 with no repeats. Second, each of the nine columns must contain 1 through 9 with no repeats. Third, each of the nine 3×3 boxes must contain 1 through 9 with no repeats. That is the entire game: place every digit so it appears exactly once in its row, its column, and its box. The puzzle begins with some cells pre-filled as fixed clues — you may not move or overwrite them. There is no arithmetic and the numbers are only symbols; you could play with nine letters or colours instead. A proper Sudoku has a single unique solution, so any cell you cannot logically deduce means you have made an error elsewhere.
Is Sudoku hard to learn?
No. The rules of Sudoku take about a minute to learn, and an easy puzzle can be solved using a single idea: find a row, column, or box that is almost complete and fill the forced cell. The difficulty is not in the rules but in how deeply you have to look. Easy puzzles fall to simple scanning; harder ones require tracking candidate numbers and spotting patterns. Because every puzzle is solvable by logic alone, you improve quickly just by playing. A good way to learn is to use a hint feature when you get stuck — our AI Hint button finds the next logical move and names the technique so you pick up the patterns naturally.
Do you need maths to play Sudoku?
No maths at all. Sudoku uses the digits 1 to 9, but you never add, subtract, or do any calculation with them. The numbers are simply nine distinct symbols, and the whole game is about logical placement — making sure each symbol appears once per row, column, and box. You could replace the digits with nine letters or nine colours and the puzzle would play identically. What Sudoku does train is logical reasoning, pattern recognition, and patience. That is why it appeals to people who do not consider themselves maths people: success comes from careful observation and deduction, not arithmetic skill.
What is the best way to start a Sudoku puzzle?
Start by scanning for the easiest wins before doing anything clever. Look across the whole grid for any row, column, or 3×3 box that already has eight numbers — the missing one is forced. Next, take a single digit, say 5, and check each of the nine boxes: if a box has no 5 yet and only one cell where a 5 can legally fit, place it. Repeat this digit-by-digit sweep. Once the obvious cells are filled, switch to pencil marks: write the small candidate numbers each empty cell could still hold, which reveals the next moves and sets up advanced techniques. Always work from certainty — if you are guessing, stop and look again.