Sudoku Tips That Actually Work (and Is There a Formula?)

Practical Sudoku tips in the order they pay off, checked against how our hint engine solves 60,000 puzzles, and an honest answer to the formula question.

Updated 2026-11-05

Is there a formula?

No. A Sudoku is not solved with arithmetic, and the digits could just as well be letters or colours: all that matters is that each one appears once in every row, column and box. What there is, is a method. Our app's hint engine solves every puzzle by trying a fixed ladder of techniques, easiest first, and taking the first one that works. Fast solvers do much the same, mostly without thinking about it.

The 45 rule, that every row, column and box adds up to 45, is true but does not help with a classic Sudoku: it only says what you already know, that each digit appears once. It matters in Killer Sudoku, where the puzzle gives you sums.

Tip 1: scan one digit at a time

Take one digit and look at each box that does not have it yet. The same digit in the rows and columns that pass through the box rules out squares; when only one square is left, the digit goes there. This habit, the hidden single, is all you need for every Medium puzzle in our bank of 60,000.

Tip 2: finish what is nearly full

A row, column or box with one or two empty squares is the cheapest place to look. On Easy puzzles it is usually enough on its own: in 95.1% of our Easy puzzles, the hardest step is a nearly complete row, column or box.

Tip 3: use notes only when you need them, then keep them complete

Notes slow you down on easy puzzles, so skip them while scanning still gives you digits. Once it stops, write every possible digit in every empty square, and after each placement remove that digit from the notes in its row, column and box. A note that should have been crossed out is a common way to go wrong; our list of common mistakes shows the others.

Tip 4: look for pairs before anything fancy

When two squares in a row, column or box can only hold the same two digits, those two digits are used up there: remove them from the other squares of that row, column or box. Pairs and the pointing pair decide most Hard puzzles in our bank: 59.6% by a pointing pair and 18.3% by a naked pair.

Tip 5: learn the patterns in the order they turn up

After pairs, the techniques that most often unlock a puzzle in our bank are the Skyscraper and the Y-Wing, not the better-known X-Wing. Our guide to getting unstuck on Hard and Expert puzzles has the full table, level by level.

Stuck on a Hard or Expert Sudoku? The Technique You Need Next →

Habits that make you faster

Place a digit only when you can say why it goes there. A lucky guess can break the puzzle many moves later.
After each placement, look at the same row, column and box again: the new digit often gives you the next move.
Stay with one digit or one box until it stops giving you moves, rather than jumping around the grid.
If nothing is impossible and nothing repeats but you are stuck, the next step needs a new technique: that is the moment to learn one.

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Practice

Every Find the Mistake puzzle on this site has exactly one wrong digit, and you can play each board right on its page.

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