How to Play Sudoku (Grid)

🔢What is Sudoku?

Sudoku is the world's favorite number puzzle — pure logic, zero arithmetic. You're given a 9×9 grid, partly filled. Complete it so that every row, column, and 3×3 box holds the digits 1–9 exactly once. On DailyGrid it's called Grid, and every puzzle is generated with a unique solution that can be reached by deduction alone — guessing is never required.

📜The rules

1. Each row must contain the digits 1–9 with no repeats.
2. Each column must contain the digits 1–9 with no repeats.
3. Each of the nine 3×3 boxes must contain the digits 1–9 with no repeats.
4. The pre-filled clue digits are fixed — they never change.
5. Fill every cell to solve. On DailyGrid you can pencil in small candidate notes in any cell while you think.

🎯Strategy

Getting started

• Scan for singles. Look at any empty cell and ask: what digits are already in its row, column, and box? If only one digit survives, place it (a naked single).
• Sweep digit by digit. Pick a digit — say 7 — and look at every row, column, and box already containing a 7. The remaining space often narrows a box to exactly one cell for its 7 (a hidden single).
• Fill the fullest houses first. Rows, columns, and boxes with the most clues give up their remaining digits fastest.

Level up

• Pencil marks. Write every candidate into every empty cell, then erase as digits are placed. Tedious for two minutes; decisive for the rest of the solve.
• Naked pairs: two cells in a house holding the same two candidates ({3,8} and {3,8}) mean 3 and 8 live in those cells — erase them from every other cell in the house.
• Pointing pairs: if a digit's candidates in a box all sit in one row, that digit can't appear elsewhere in that row outside the box.
• X-wing (for hard days): if a digit has exactly two candidate columns in two different rows, forming a rectangle, it can be erased from those columns in all other rows.

Pro tips

• Never guess. A guess that happens to work teaches nothing and usually detonates ten moves later — candidates are the fastest honest path.
• When scanning stalls, re-pencil: most stalls are a stale candidate list, not a hard puzzle.
• Track your solve times — Grid's skill rating rewards beating par, and clean scanning (not faster guessing) is what moves it.

⚠️Common mistakes

• Checking only rows and columns and forgetting the 3×3 box — the box causes most "impossible" grids.
• Leaving early mistakes in place. Because DailyGrid puzzles have one solution, a contradiction always means your digit is wrong somewhere — backtrack to the least-certain placement.
• Skipping pencil marks on medium days. The techniques above all run on candidates.

❓FAQ

What are the rules of Sudoku?

Every row, column, and 3×3 box contains 1–9 exactly once. Clues are fixed; the DailyGrid puzzle has exactly one solution, reachable by logic alone.

What's the best beginner strategy?

Scan for naked and hidden singles, then use pencil marks and pairs. See the strategy section above.

Is the DailyGrid Sudoku free?

Yes — it's called Grid, and a new one drops every day at midnight ET, no account needed — the daily puzzles are free. Always. One of ten daily puzzles on DailyGrid.

Where can I learn the other games?

See all ten DailyGrid guides.