How to Play Sudoku for Beginners: A Complete Step-by-Step Guide
Sudoku a Day Blog ·
If you have never played Sudoku before, the grid can look like a jumble of numbers with no obvious starting point. But once you understand three simple rules and two solving moves, the puzzle unlocks completely. This guide covers everything you need as a beginner — the rules, your first moves, what to do when you get stuck, and a 7-day practice plan to build real skill.
Want to follow along interactively? Open our how-to-play guide in a second tab and try each technique live as you read.
The Three Rules of Sudoku
Every Sudoku puzzle — whether easy or expert — follows exactly the same three rules:
- Each row must contain the digits 1 through 9, with no repeats.
- Each column must contain the digits 1 through 9, with no repeats.
- Each 3×3 box must contain the digits 1 through 9, with no repeats.
The 9×9 grid is divided into nine 3×3 boxes (sometimes called regions or blocks). Each box, each row, and each column is a "unit." A solved puzzle has every unit containing exactly the digits 1 through 9, no more, no less.
The puzzle starts with some cells already filled in — these are called "givens" or "clues." Your job is to fill in the remaining empty cells using logic alone. There is always exactly one correct solution.
One more thing worth knowing early: no maths required. You never add, subtract, or multiply. The digits 1–9 are just symbols. You could replace them with letters A–I and the puzzle would work identically.
Understanding the Grid Before You Start
Before you place your first digit, spend 30 seconds looking at the given clues. Ask yourself:
- Which digits appear most often? (Heavily represented digits are usually easiest to place.)
- Are there any rows, columns, or boxes that are nearly full? (One or two empty cells left means easy placements are available.)
- Is there any digit that appears in eight out of nine rows or columns already? (If 7 is present in eight rows, you can often place the missing 7 immediately.)
This quick scan takes less than a minute and tells you where to begin. Always start with the easiest moves — fully solving one cell often opens up more placements nearby.
Your First Move: Nearly Complete Units
The simplest move in Sudoku is filling a unit (row, column, or box) that already has eight of its nine digits filled in. The missing digit is whichever number from 1–9 is not yet present.
For example: if a row contains 2, 3, 4, 5, 6, 7, 8, 9 and one empty cell, the missing digit is 1. Fill it in.
Most beginner puzzles give you several of these immediately. Work through every nearly complete unit before moving on to anything more complex. These free placements often create new nearly complete units in adjacent rows, columns, or boxes — follow the chain until it runs out.
Technique 1: Scanning
Scanning is the most fundamental Sudoku technique. It works like this:
- Pick one digit — say, 5.
- Look at all the 5s already placed on the grid. In any row, column, or box that already contains a 5, no other cell in that unit can hold another 5.
- For each 3×3 box that does not yet have a 5, eliminate every cell that shares a row or column with an existing 5. If only one cell remains uneliminated in the box, place your 5 there.
Repeat this process for each digit from 1 to 9. This single technique solves a large portion of easy puzzles without any further moves needed.
Example: Digit 3 already appears in row 1, row 4, and row 7. In a box that spans rows 4–6 and columns 7–9, you can eliminate all cells in row 4 (already has a 3) and any cells in columns that already contain a 3. If only one cell in that box remains eligible, place the 3 there.
Technique 2: Naked Singles (Elimination)
When scanning does not immediately give you a placement, flip your perspective and look at individual cells instead of individual digits.
For any empty cell, ask: which digits are already used in this cell's row, column, and box? Cross out those digits mentally. If only one digit from 1–9 is not yet used in any of the cell's three units, that digit must go in this cell. This is called a naked single.
Example: An empty cell sits in row 5 (which already has 1, 2, 4, 6, 7, 8, 9), column 3 (which has a 3), and its box (which has a 5). Combining: 1, 2, 3, 4, 5, 6, 7, 8, 9 are all accounted for — except for 3 and 5 being covered by column and box respectively. If the only remaining digit is one number, you have your naked single.
Together, scanning and naked singles are enough to solve most easy Sudoku puzzles from start to finish. Practice these two moves until they feel automatic.
Pencil Marks: Your Secret Weapon
Once you have exhausted the obvious placements, the next step is to use pencil marks (also called candidate marks or notes).
For every empty cell, write small candidate digits — one for each number that is still possible given the cell's row, column, and box. On paper, write them lightly in pencil; in a Sudoku app, use the notes mode.
As you place digits elsewhere on the grid, return to pencil-marked cells and cross out newly eliminated candidates. When a cell's candidates reduce to just one, place that digit.
Pencil marks transform complex puzzles from overwhelming to manageable. You are not guessing — you are systematically narrowing possibilities until the answer becomes clear. Many beginners skip pencil marks and instead try to hold everything in their head. This leads to errors and frustration. Use them.
A good rule of thumb: if you have been working on a puzzle for more than five minutes without a new placement, stop and add pencil marks to every unsolved cell before continuing.
What to Do When You Get Stuck
Getting stuck is normal, especially on medium puzzles. Here are four moves to try, in order:
1. Add or Review Your Pencil Marks
If you have not added candidate marks yet, do it now for every empty cell. If you have them, scan for any cell whose candidates have reduced to a single digit — place it.
2. Scan All Digits Again
Re-run the scanning technique for every digit 1–9. A digit you placed earlier may have eliminated candidates elsewhere, opening a new placement you missed.
3. Look for Hidden Singles
In each row, column, or box, check whether any digit appears as a candidate in only one cell. Even if that cell has multiple candidates, if it is the only place in its unit where a particular digit can go, place that digit there. This is called a hidden single and it is very common in medium puzzles.
4. Look for Naked Pairs
If two cells in the same unit contain exactly the same two candidates (for example, both show only 4 and 7), then those two digits must go in those two cells — in some order. You can safely remove 4 and 7 as candidates from every other cell in that unit. This often unlocks nearby placements. For a full breakdown of this technique, see our guide on common Sudoku mistakes and how to fix them, which covers naked pairs in detail.
What Not to Do When Stuck
Do not guess. Every well-formed Sudoku puzzle has exactly one solution reachable by pure logic. Guessing introduces errors that cascade through the grid and are very difficult to trace. If you are genuinely stuck after trying all four steps above, the puzzle may be harder than your current skill level — and that is fine. Come back to it after completing easier puzzles and building more pattern recognition.
For a list of the most common beginner errors and how to avoid them, see: The Most Common Sudoku Mistakes and How to Fix Them.
Understanding Difficulty Levels
Sudoku puzzles are typically rated easy, medium, hard, and expert. The difference is not just how many clues are given — it is which techniques are required to solve them.
- Easy: Scanning and naked singles are enough. Every cell can be solved in a logical order with no dead ends.
- Medium: Requires hidden singles, locked candidates, and often naked pairs. Pencil marks are essential.
- Hard: Needs more advanced techniques like naked triples, X-Wings, or pointing pairs.
- Expert: Requires chaining techniques, forcing chains, or trial-and-error for some solvers.
As a beginner, stay on easy until you can complete them consistently without errors. There is nothing wrong with staying there for weeks — the pattern recognition you build on easy puzzles directly transfers to medium. For a deeper look at what separates difficulty levels, see our difficulty guide.
A 7-Day Practice Plan for Beginners
The fastest way to learn Sudoku is consistent daily practice — short sessions are more effective than long irregular ones. Here is a structured plan to take you from your very first puzzle to comfortable medium solving in one week.
| Day | Goal | Activity |
|---|---|---|
| Day 1 | Learn the rules | Read this guide. Complete 1 easy puzzle, taking as long as you need. |
| Day 2 | Practise scanning | Complete 2 easy puzzles. After each, review where scanning alone placed cells. |
| Day 3 | Practise naked singles | Complete 2 easy puzzles. For every placement, name the technique you used. |
| Day 4 | Introduce pencil marks | Complete 2 easy puzzles using full pencil marks from the start. |
| Day 5 | Speed and accuracy | Complete 3 easy puzzles timed. Aim for zero errors per puzzle. |
| Day 6 | First medium puzzle | Attempt 1 medium puzzle with full pencil marks. It is fine if you do not finish — notice where you get stuck. |
| Day 7 | Build the habit | Complete 1 easy + 1 medium puzzle. Aim for consistent daily solving going forward. |
After week one, keep a daily puzzle as a routine. Consistency beats intensity: five minutes every day builds faster pattern recognition than 45 minutes once a week. Play a free easy Sudoku online each morning to keep the habit low-friction.
Tips to Improve Faster
- Always finish easy puzzles without errors before moving up. Accuracy first, speed second.
- Never guess. If you are about to guess, add pencil marks and look for hidden singles instead.
- Review completed puzzles. After finishing, look back at the cells you filled last — they often reveal techniques you can apply earlier next time.
- Vary between paper and digital. Paper puzzles slow you down (in a good way) and force deliberate thinking. Digital gives you instant error checking and candidate marks. Use both.
- Practise with printables. Printed grids are great for travel and breaks. Download our free printable Sudoku puzzles in easy, medium, and hard.
Frequently Asked Questions
How do you play Sudoku for beginners?
Place the digits 1–9 in every row, every column, and every 3×3 box so that no digit repeats in any unit. Start by finding rows, columns, or boxes with only one empty cell — fill the missing digit. Then scan digit by digit to find cells where only one number fits. No maths is needed, only logic.
What is the easiest way to solve Sudoku for beginners?
The two core beginner moves are scanning (pick a digit, trace where it already appears, find the one cell in each unit where it must go) and naked singles (for each empty cell, count which digits are already used in its row, column, and box — if only one digit is left, place it). These two techniques solve most easy puzzles completely.
How do you solve Sudoku when stuck?
Add pencil marks to every empty cell, then look for any cell whose candidates have reduced to one number. If still stuck, scan each digit across all units to find a hidden single. For medium puzzles, look for naked pairs: two cells in the same unit with the same two candidates, which lets you remove those digits from other cells in that unit.
How long does it take to learn Sudoku?
Most beginners finish their first easy puzzle within 20–40 minutes of learning the rules. After five to ten easy puzzles, you will begin to recognise patterns automatically. A structured 7-day plan — starting on easy and graduating to medium by day 7 — builds solid, lasting skills.
Do you need to be good at maths to play Sudoku?
No. The digits 1–9 are symbols only — you never add, subtract, or calculate. The puzzle is entirely about logic and elimination. If you can count to 9, you can learn to play Sudoku.