How to play sudoku
Practice on the live grid above: fill 1–9 so every row, column, and 3×3 box has each digit once. Pencil for candidates; Hint when you want a named next step.
Play instantly · No signup · Runs in your browser
On this page
How to play sudoku
Sudoku is a 9×9 number grid. Some cells start filled (givens). You fill the rest with digits 1 through 9 so that every row, every column, and every 3×3 box contains each digit exactly once. No arithmetic beyond counting to nine — the tension is logic and patience.
The board above follows those rules. Skim below if you are new; skip if you already pencil-mark in your sleep.
When
When to use
First time; teaching someone in one screen; checking phone vs keyboard controls.
When not
When not to
You already finish hard grids and want habits → sudoku strategy. You want sum cages → killer sudoku. You came for a brutal puzzle → evil sudoku.
Defaults
Assumptions
Classic 9×9. Givens cannot be overwritten. A valid puzzle has one solution. Empty cell ≠ “any digit”; it must satisfy all three constraints.
Steps
How
- Pick an empty cell; look at its row, column, and box — which digits are missing?
- If only one digit fits, place it (a naked single).
- Turn on Pencil to note candidates; erase notes when a digit is placed.
- Stuck → Hint (technique name + reason). New puzzle for another easy/medium teaching grid.
Worked notes
Examples
- A box is missing only 7 → every empty cell in that box that can see a 7 elsewhere is blocked, so the last open cell in the box gets 7
- You place a 5 that already exists in the same row → Check / conflict highlight should catch it; fix before digging deeper
Watch-outs
Gotchas
- Guessing early feels fast and usually ruins uniqueness work — prefer candidates.
- “How to play” articles elsewhere are often text-only; this page keeps a live grid.
- Harder labels (hard/evil) are not different rules — same constraints, fewer easy singles.
Nearby pages
Compare
Strategy depth: sudoku strategyKiller variant: killer sudokuJust play: home
Controls
Quick controls
- Hint — a cell/digit, technique name, and short reason.
- Check — flags conflicts without revealing the full grid.
- Pencil — candidate notes for empty cells.
- New puzzle — same difficulty band, fresh seed.
- Daily — fixed local seed for the calendar day.
- Erase — clear the selected cell (not givens).
FAQ
Common questions
What is the goal?
Fill the grid so every row, column, and box has 1–9 once.
Keyboard or touch?
Both. Tap a cell, then 1–9 (or use keys when focused).
What does Hint do?
Suggests a placement or elimination with a technique name and a short reason.
Download required?
No. Browser only.