Sudoku Tips
Twelve practical habits that make every solve faster and calmer — from your first easy grid to expert puzzles.
Getting started
- Start with the most common digit. Count which digit already appears most often and scan it through all nine boxes first. Each placement makes the next one easier.
- Scan by box, then by line. Cross-hatching a box catches most early placements. When boxes stop giving, check each row and column for a digit with only one possible cell.
- Re-scan after every placement. A new digit blocks cells in its row, column and box — the cells around it are the most likely to produce the next single.
- Never guess. A proper Sudoku has one solution reachable by logic. If you cannot prove a digit, look for another one instead.
Pencil marks done right
- Delay full notes on easy grids. Scanning is faster while there are lots of clues. Switch to notes when scanning stalls.
- Be complete or be careful. A missing candidate is worse than no notes at all, because it leads to a false 'single'. When you write notes for a cell, write all of them.
- Clean up as you go. Every time you place a digit, erase it from the notes of its row, column and box. (On Sudoku.tips this happens automatically.)
- Look for two-candidate cells. Cells with just two options are the raw material for naked pairs, X-Wings and XY-Wings.
When you get stuck
- Work through the techniques in order. Singles, then pairs and locked candidates, then fish and wings. The techniques guide lists them from easiest to hardest.
- Focus on one digit at a time. Highlight every copy of a digit and look for pointing pairs, X-Wings and Swordfish in that digit alone.
- Take a short break. Fresh eyes often spot a single you looked straight past.
- Use a hint that teaches. Instead of revealing the answer, use the solver's Next step button to see the next deduction and its technique name.
If you make a mistake on paper, it can ripple through the grid. Online, use Undo to step back to before the wrong entry rather than starting over.
Frequently asked questions
What is the best strategy for Sudoku?
Use the simplest technique that works: scan for singles first, add pencil marks when scanning stops, then look for pairs and locked candidates, and only reach for advanced patterns when those run out.
How can I get faster at Sudoku?
Practise one level until it feels routine, scan systematically digit by digit, and learn to recognise hidden singles in rows and columns — they are the most common deduction after scanning.
Should I always use pencil marks?
Not on easy puzzles, where scanning is quicker. From medium upwards, complete and accurate notes make hidden patterns much easier to see.