Play Sudoku Pro Online: The Ultimate Number Puzzle

Whether you are looking to sharpen your mind with your morning coffee or need a relaxing brain-teaser to unwind, Sudoku Pro is the perfect challenge.

Despite using numbers, Sudoku requires absolutely no math skills. It is a game of pure deduction, spatial reasoning, and logic. With our built-in puzzle generator, you can play infinite levels ranging from a breezy Easy mode to a brain-bending Hard mode.

Choose your difficulty below and start filling the grid!

How to Play Sudoku (Rules for Beginners)

The goal of Sudoku is to fill a 9×9 grid with digits so that every column, row, and 3×3 section contain the numbers between 1 and 9.

At the start of the game, the grid will have some squares already filled in. Your job is to use logic to fill in the missing digits and complete the grid. To win, you must strictly follow these three rules:

1. Row Rule: You cannot repeat any numbers from 1 to 9 within the same horizontal row.
2. Column Rule: You cannot repeat any numbers from 1 to 9 within the same vertical column.
3. Box Rule: You cannot repeat any numbers from 1 to 9 within the same 3×3 square (outlined by the thicker borders).

(To play the game above, simply click or tap an empty square to select it, then use the on-screen number pad or your keyboard to fill in your guess. The square will turn red if your number breaks one of the three rules!)

Winning Strategies: How to Solve Sudoku Puzzles

Staring at a mostly empty grid can be intimidating. Instead of guessing, use these proven strategies to find the correct numbers:

1. The “Cross-Hatching” Technique

This is the best way to start any puzzle. Pick a number (let’s say 1) and look at the three 3×3 boxes across the top of the board. If the left box has a 1 in the top row, and the middle box has a 1 in the bottom row, you know the right box must have its 1 in the middle row. Scan the columns below it to see if you can pinpoint the exact square.

2. Look for the “Naked Singles”

As the board fills up, look for rows, columns, or 3×3 boxes that are almost entirely complete. If a row already has eight numbers filled in, the final empty square is a “naked single”—it has to be the one missing number! Always grab these easy wins first.

3. Focus on the Most Crowded Areas

Don’t start in an area of the board with mostly empty white squares. Focus your attention on the 3×3 boxes that already have 5 or 6 numbers filled in by the computer. The fewer empty squares there are, the fewer possibilities exist, making it much easier to deduce the correct answer.

Looking for a Different Challenge?

If you have mastered the 9×9 grid and want to try a puzzle that mixes Sudoku logic with a little bit of math, you have to try Kakuro Pro. Or, if you want to test your spatial reasoning, try building bridges in Hashi Pro