The most important Sudoku tip: work in order
Most Sudoku tips are really one strategy: try techniques in the right order, cheapest first, expensive only when needed. All effective Sudoku strategies build on that order. Every technique below has a full lesson with step-by-step examples; this page shows you when to use each one.
If you are brand new, start with How to Play Sudoku and the step-by-step solving method first.
Level 1: Placements you can see without notes
These techniques place digits directly and require no pencil marks. They solve most easy puzzles on their own and remain your bread and butter at every difficulty.
Level 2: Work with candidates
From medium difficulty, you need to track which digits can still go in each cell. Learn to write pencil marks selectively and keep them updated; every technique above level 2 depends on their accuracy.
Level 3: Eliminations inside boxes and lines
The first elimination techniques remove candidates rather than place digits. Locked candidates uses box-line intersections; pairs and triples use small groups of cells that reserve digits between them. These carry you through most hard puzzles.
Level 4: Advanced patterns
Evil-level puzzles occasionally demand grid-wide patterns: fish patterns that track one digit across multiple lines, and wings built from bi-value cells. They are rarer, so search for them only after the earlier levels are exhausted.
Match your technique to the difficulty
If a puzzle resists, the fix is usually one level up from what you are using, not three. Escalate one technique at a time and return to cheap scanning after every elimination.
- Easy: Full House plus hidden and naked singles are enough.
- Medium: add pencil marks and locked candidates.
- Hard: add naked and hidden pairs and triples.
- Evil: add X-Wing, Swordfish, and XY-Wing.
Habits that make you faster
Follow one digit at a time across the grid instead of staring at one cell. Use highlighting to make a digit's positions visible at a glance. Harvest all cheap moves after every placement, and keep pencil marks honest: an outdated candidate costs more time than writing none at all.
Frequently asked questions
What is the best Sudoku strategy for beginners?
Master Full House, hidden singles, and naked singles before anything else. They are simple, always safe, and solve entire easy puzzles.
Do I need advanced techniques for every hard puzzle?
No. Most hard puzzles fall to singles, locked candidates, and pairs. Advanced patterns like X-Wing are needed mainly at evil difficulty.
How do I know which technique a puzzle needs?
Escalate gradually: when scanning stops working, add pencil marks; when singles stop appearing, look for eliminations, starting with locked candidates.
Practice next
Strategy sticks when it is tested. Pick the difficulty that matches your current level and climb one step at a time.