How to Play Sudoku: Complete Beginner's Guide

Sudoku is a logic puzzle on a 9×9 grid. Your goal: fill every cell so that every row, every column, and every 3×3 box contains the digits 1 to 9 — each exactly once. No arithmetic needed. If you've never played before, start with the three rules below, then follow the 7-step walkthrough.

Step-by-step visual walkthrough

1. Step 1: Understand the grid

   You're looking at a 9×9 grid of cells, grouped into nine 3×3 boxes. Some cells are pre-filled - these are your givens (clues). They're fixed. Everything else is yours to solve.

2. Step 2: Learn the three constraints

   The entire game is built on three rules:

   1. Each row contains 1–9, no repeats.
   2. Each column contains 1–9, no repeats.
   3. Each 3×3 box contains 1–9, no repeats.

   Every move you make must satisfy all three simultaneously.

3. Step 3: Scan for easy cells first

   Look for rows, columns, or boxes that already have many givens. The fewer empty cells, the fewer candidates - making the right number easier to find.

   One empty cell in this row - must be 2.

4. Step 4: Use pencil marks (candidates)

   When a cell has more than one possible value, jot down small candidate numbers in the corners. This is how every serious solver works, at every difficulty level. How to use pencil marks without slowing down →

5. Step 5: Eliminate and place

   Cross off candidates that appear elsewhere in the same row, column, or box. When only one candidate remains in a cell — place it (a naked single). When a number can only fit in one cell within a group — that's where it goes (a hidden single). These two techniques alone solve every easy puzzle.

   7 can only go in the highlighted cell - every other cell is eliminated by the surrounding row or column.

6. Step 6: Build momentum — and what to do when you get stuck

   Each number you place opens new eliminations elsewhere. The puzzle accelerates as you go. If progress stops, work through this rescue sequence:

   1. Re-scan every row, column, and box for naked singles — cells where only one candidate remains.
   2. Update your pencil marks — each number you just placed may eliminate candidates you haven't crossed off yet.
   3. Look for hidden singles — a digit that fits in only one cell within a group, even if that cell still shows other candidates.
   4. Try a different region — sometimes one area of the grid unlocks another.

   Still stuck after all four? The full stuck-guide covers 8 structured rescue techniques including naked pairs, pointing pairs, and when — and how — to use backtracking.

7. Step 7: Verify your solution

   When the grid is full, confirm: every row, every column, every 3×3 box contains 1–9 with no repeats. Congratulations. 🎉

What to learn next

The clearest next step: work through the technique ladder below. Or pick a destination from this list:

• 📘 Sudoku for beginners - deeper dive into how to think about puzzles
• 🧾 Download the Complete Beginner's Guide (PDF) - a printable walkthrough for your first puzzles
• 📚 Full library: Sudoku strategies guide
• 📋 Quick-reference: printable strategy reference — every technique from beginner to expert on one page
• 🔀 Try something different: Sudoku variants - Killer, Diagonal, Samurai and more
• 🖨️ Practice on paper: Free printable Sudoku puzzles or blank grid for practice
• 🏫 Using Sudoku in class? Free printable Sudoku for teachers — graded worksheet packs with answer keys
• 📱 Play now: Download the Sudoku a Day app - one calm, ad-free puzzle every day

Beginner strategy pathway

Once you can scan and place easy cells, learn these techniques in order — each one unlocks puzzles the previous one can't solve:

1. Naked singles — a cell where only one candidate remains after checking its row, column, and box. The foundation of every solve.
2. Hidden singles — a digit that fits in exactly one cell within a row, column, or box, even if other candidates are present. Solves most easy puzzles on its own. See also: hidden singles strategy guide.
3. Naked pairs — two cells in the same group share exactly the same two candidates. Use them to eliminate those digits from every other cell in that row, column, or box.
4. Pointing pairs — when a digit inside a box is restricted to one row or column, it can be removed from the rest of that line outside the box. The key to unlocking medium puzzles.
5. X-Wing — a candidate appearing in exactly two cells across two rows, aligned in the same columns, can be eliminated from those columns everywhere else. Essential for hard and expert puzzles.

All beginner techniques in one place →  ·  Play an easy Sudoku now to practise →

How to play Sudoku - FAQ