Sudoku247Wiki
Sudoku247Wiki is a free, independent reference for sudoku: the rules of every variant, the basics for new players, all 25 solving techniques, and the guides that pull it together. No accounts, no ads, no fluff.
Explore the wiki
Four clusters cover the whole game. Pick the one that fits where you are.
Sudoku Basics
The vocabulary on-ramp — parts of the grid, candidates, pencil marks, notation and difficulty bands. Read first if you are new.
2How to Play Sudoku
The rules pillar plus the seven per-variant rules pages: classic, killer, jigsaw, sudoku X, wordoku, 6×6 mini and 4×4 kids.
3Solving Techniques
Twenty-five deduction rules grouped beginner to expert, each with a worked example on a real grid.
4Solving Guides
Practical, end-to-end how-tos: the solving order, how to solve faster, common mistakes and a practice plan.
Popular techniques
Naked Single
A cell with only one possible candidate left — the most fundamental solving move in Sudoku.
Hidden Single
A digit that fits in only one cell of a row, column, or box — even when that cell still has other candidates.
Naked Pair
Two cells in a unit sharing the same two candidates lock those digits out of every other cell in that unit.
Hidden Pair
Two digits that can go in only the same two cells of a unit — clearing all other candidates from those cells.
Naked Triple
Three cells in a unit whose candidates together use only three digits lock those digits out of the rest of the unit.
Hidden Triple
Three digits that can live in only the same three cells of a unit — clearing every other candidate from those cells.
Sudoku variants
About this wiki
Sudoku247Wiki is a free, independent reference for the whole game of sudoku — the rules of every variant, the basics for new players, all 25 solving techniques, and the guides that tie them together. Plain English, no accounts, no ads.
Use the cards below to jump straight to a cluster, or read about the wiki to see how it is built, how it is funded, and where to begin.
Frequently asked questions
- What is Sudoku247Wiki?
- Sudoku247Wiki is a free, independent reference for sudoku. It carries the rules of every popular variant, the basics every new player needs (parts of the grid, candidates, pencil marks, notation, difficulty bands), all 25 solving techniques from naked single to forcing chains, and the practical guides that string them together. No account, no paywall, no advertising — read any page directly. The play hub at sudoku247online.com is a sibling site for actually solving puzzles; the wiki is the part you read.
- Is sudoku247wiki.com free?
- Yes — every page is free to read with no account, no paywall and no advertising. The wiki is funded by the sister play hub (sudoku247online.com) so the reference itself can stay clean. You will never see a "create an account to continue reading" wall or an ad break mid-article. The only thing we ask is that if you find the wiki useful, you give the play hub a try when you want to solve a puzzle.
- Where do I start if I have never solved a sudoku?
- Start with what is sudoku for the one-minute orientation, then read grid anatomy to learn the names of the parts of the grid. From there, how to play covers the rules in plain English. Then pick up your first solving move with the naked single, pair it with the hidden single, and finish with the guided solve in the first puzzle walkthrough. About thirty minutes of reading and you can finish most easy puzzles unaided.
More from the wiki
Practice online
Put it into practice on free puzzles with hints, notes and four difficulty levels.
Play Sudoku