How to Play Daily Sudoku

Sudoku is a number puzzle you solve with logic alone. Every row, every column and every box must contain each digit exactly once. This guide covers the rules, every button in the game above, how the difficulty levels work and the solving techniques the hints teach.

The goal and the three rules

A standard Sudoku board is a 9 by 9 grid split into nine 3 by 3 boxes. Some cells already hold a number. These are the clues, and they never change. You fill in every empty cell using three rules:

1. Each row contains the digits 1 to 9 once each.
2. Each column contains the digits 1 to 9 once each.
3. Each 3 by 3 box contains the digits 1 to 9 once each.

The smaller Mini boards work the same way with fewer digits. A 4 by 4 board uses 1 to 4 and 2 by 2 boxes. A 6 by 6 board uses 1 to 6 and boxes that are 2 cells tall and 3 wide.

A first move you can make right now

Using the Game

Choosing a puzzle

The tabs at the top of the widget switch between modes:

• Learn to play is a short narrated lesson on a 4 by 4 board. It explains the rules, then solves the puzzle step by step with highlighted cells. Use Play, Pause, Next step, Restart, Speed and Voice to control it. Voice uses your browser’s built-in speech and can be switched off.
• Mini 4×4 and Mini 6×6 are quick puzzles that take a few minutes.
• Easy, Medium and Hard are the full 9 by 9 daily puzzles.
• Your puzzle lets you enter or paste a puzzle from anywhere and solve it with the same tools.

A ✓ on a tab means you have solved that puzzle today, and a ★ means you solved it cleanly.

Entering numbers

Tap a cell, then tap a digit on the number pad. The small number under each pad digit shows how many are still to place, and it turns into a check mark when all of that digit are on the board. Tap the same digit again to clear a cell, or use Erase. The selected cell’s row, column and box are shaded, and cells holding the same digit are marked so you can scan for it.

Any digit that repeats in a row, column or box turns red straight away. A wrong digit that clashes with nothing is not marked, but it still counts as a mistake.

Pencil notes

• Notes switches the number pad to pencil marks. Tap digits to toggle small candidate numbers in the selected cell.
• Auto notes fills in every candidate that is still possible in every empty cell.
• Clean notes removes pencil marks that are no longer possible, without adding new ones.
• Placing a correct digit clears that digit from the notes of every cell that sees it.

Undo, erase, check and pause

• Undo steps back one entry or note change. It does not reduce your mistake count.
• Check marks wrong cells in red for a few seconds. It costs 10 seconds on your score and rules out a clean solve.
• Pause stops the timer and hides the board so nobody can study it. The timer also stops when you switch to another browser tab.
• Reset puzzle clears your entries for the current puzzle after a second tap to confirm.

Hints that explain themselves

Press Hint and the game finds the next logical step, tells you why it works and highlights the cells involved. A typical hint reads: “Only a 7 fits in this cell. Every other digit is already used: 1, 3 in its row; 2, 9 in its column; 4, 5, 6 in its box.” Each hint adds 30 seconds to your score and rules out a clean solve. Prefer to play without them? Switch Hints off and the button is disabled.

Keyboard shortcuts

• 1 to 9 enter a digit in the selected cell
• Backspace, Delete or 0 erase it
• N switches pencil notes on and off
• Arrow keys move between cells, and Tab reaches the board

Score, timer and the clean-solve star

The timer starts the first time you tap the board, so reading these instructions is free. Your score is your time plus penalties: 15 seconds for each mistake, 30 for each hint and 10 for each use of Check. Lower is better. A solve with no hints, no mistakes and no checks is a clean solve and earns a ★ on its tab.

Difficulty Levels Explained

Difficulty here is decided by the techniques a puzzle needs, not by how many numbers were left on the board. Every Easy, Medium and Hard puzzle has exactly one solution and can be solved by logic with no guessing.

New to Sudoku? A good order is Learn to play, then Mini 4×4, Mini 6×6 and Easy. Move up when Easy stops feeling like work.

Sudoku Solving Techniques

These are the techniques the hints use, in the order you will meet them. Each one removes guesswork by showing that a digit has to go in one place or cannot go in another.

Naked single

A cell where eight of the nine digits are already ruled out by its row, column and box, leaving one possible digit. In the example above, the top row left only a 2 for the first cell.

Hidden single

Within a row, column or box, a digit that has only one cell left where it can go. The cell may have other candidates, but that digit has nowhere else to be, so it must go there.

Locked candidates

This comes in two forms. In a pointing pattern, every possible spot for a digit inside a box lies on one row or column, so that digit can be removed from the rest of that row or column. In a box-line pattern, every possible spot for a digit in a row or column lies inside one box, so it can be removed from the rest of that box.

Naked pair

Two cells in the same row, column or box that can each only hold the same two digits. Those two digits must fill those two cells, so they can be removed as candidates from every other cell in that row, column or box.

Hidden pair

Two digits that can only go in the same two cells of a row, column or box. Those two cells must hold those two digits, so every other candidate can be removed from them.

X-wing

A digit that has exactly two possible cells in each of two rows, and those cells line up in the same two columns. The digit must end up in one diagonal pair of the four cells, so it can be removed from every other cell in those two columns. The same idea works with columns and rows swapped.

Players, Challenges and Streaks

Players and head-to-head

You can add up to four players on one device with + Add player. Each player has their own progress, stats and streak. Use Rename to change a name and Remove to delete a player and their data, after a second tap to confirm. With two or more players, a head-to-head panel shows everyone’s status and score on the current daily puzzle, and the lowest score wins. Share scoreboard copies the ranking so you can paste it into a message.

Challenge links

When you finish a daily puzzle, Share result creates a message with a challenge link. Anyone who opens it gets the same puzzle and sees your score, and when they finish the banner shows who won and by how much. Leave challenge returns to your own page. Challenge links carry only a date, a level, a score and a name, so nothing is stored on a server.

Streaks, the freeze and the calendar

Solve at least one daily puzzle a day to build your streak. If you miss exactly one day, the streak freeze covers it the next time you solve, once per calendar week. The 28-day calendar shows solved days in green and days covered by the freeze in gold.

Practice puzzles

New practice puzzle gives you a fresh random board at the same level whenever you want more. Practice puzzles do not count toward stats, streaks or head-to-head, and Back to today’s puzzle returns you to the daily one without losing your progress.

Solving a puzzle from somewhere else

Open Your puzzle, tap in the numbers or paste 81 characters with 0, a dot or a dash for blanks, then press Start solving. The game rejects grids with clashing clues, fewer than 17 clues, or more than one solution, and tells you which. Once it starts, you get notes, undo, check and the full hint system. Your own puzzles are kept out of the stats and the streak.

Your data stays on your device

Progress, stats, players and settings are saved in your browser only. There is no account, so clearing site data, using a private window or switching devices starts you fresh. Reset all data erases everything saved for the game on this device, after a second tap to confirm.

Tips for Faster Solving

• Start with the fullest units. Rows, columns and boxes that already hold six or seven digits give up their last cells quickest.
• Scan by digit. Pick one digit, find where it already sits, and see which empty cells in each box it can still reach. Tap a cell holding that digit to highlight all of its copies.
• Use notes for the hard cells only. Filling every candidate on an Easy board slows you down. Switch on Auto notes when you are stuck and need to look for pairs or locked candidates.
• Never guess. Every daily puzzle has a logical path. If you cannot see one, take a hint and read the reason, because that is how the techniques stick.
• Watch your penalties. A mistake costs 15 seconds, more than a hint’s time saved on an easy step. Slow down on entries and speed up on scanning.
• Come back daily. The puzzles rotate every day, and the streak and calendar make a short daily habit easy to keep.

Questions and Answers

Is Daily Sudoku free to play?

There is no account, sign-up or download. The game runs entirely in your browser on this page.

Is the daily puzzle the same for everyone?

Yes. Each puzzle is generated from the date and the difficulty, so everyone with the same date on their device gets the same Easy, Medium, Hard and Mini puzzles. That is what makes scores and challenge links comparable.

When does a new puzzle appear?

At midnight on your own device’s clock. Because the date comes from your device, someone in a different time zone can briefly be on a different day’s puzzle.

Does every puzzle have exactly one solution?

Yes. While a puzzle is being built, every clue removal is checked so that exactly one solution remains. The Easy, Medium and Hard puzzles can also be solved by logic alone, with no guessing.

How are the difficulty levels decided?

By the techniques a puzzle needs, not by the number of clues. Easy can be solved with naked singles alone. Medium needs hidden singles as well. Hard needs locked candidates or pairs. The Mini puzzles are smaller boards and are not graded.

What counts as a mistake?

Entering a digit that does not match the puzzle’s solution, even if it does not clash with another digit yet. Digits that repeat in a row, column or box turn red straight away, but a wrong digit that clashes with nothing is still counted as a mistake.

What is a clean solve?

A solve with no hints, no mistakes and no uses of the Check button. Clean solves earn a star on the puzzle’s tab and are counted in your stats.

How does the streak freeze work?

Your streak counts consecutive days with at least one daily puzzle solved. If you miss exactly one day, the freeze covers it the next time you solve, once per calendar week. A second gap in the same week resets the streak to 1.

Where is my progress saved?

Only in your browser on this device. Clearing site data, using a private window or switching devices starts you fresh, and there is no account to sync across devices.

Can I solve a puzzle from a newspaper or another app?

Yes. Open the Your puzzle tab and either tap the numbers into the grid or paste 81 characters, using 0, a dot or a dash for blanks. The puzzle needs at least 17 clues and exactly one solution. You then get notes, undo and the step-by-step hints.

Why did a hint fill in a cell for me?

The hints explain singles, locked candidates, pairs and X-wing. If a puzzle you entered needs something beyond those, the hint says so and fills in the cell instead. The daily Easy, Medium and Hard puzzles never need that.

Can I play against a friend?

Yes, in two ways. Add players on one device and compare scores on the same daily puzzle in the head-to-head panel, or finish a puzzle and use Share result to send a challenge link that loads the same puzzle for them.