--- title: "Hard Sudoku: Play Free Online, No Ads | Sudoku Flow" description: "Play Hard Sudoku free in your browser, with notes, undo and hints and no ads. Every puzzle has one answer and is graded by the technique it needs." url: https://sudokuflow.com/play/hard/ language: en --- # Hard Sudoku Free Hard Sudoku puzzles to play right here, with no ads and no sign-up. When you finish one, New puzzle gives you the next; your progress stays on this device. ## Hard · #1 Daily Sudoku grid: ```text 3 6 4 | . . . | . . 7 . . 5 | . . . | . . 4 . 9 . | 3 . . | 1 2 . ------+-------+------ . . 2 | . 7 . | . 8 . 6 . 8 | 5 9 3 | . 7 . . . . | . . . | 6 . 1 ------+-------+------ 2 . 3 | . 5 9 | . 1 . . . . | 7 3 . | . . . . 8 6 | . 2 . | . . . ```
What does this puzzle need?
## What Hard puzzles ask of you We re-solved all 10,000 Hard puzzles in the app with its hint engine, always taking the easiest step that works. This is the hardest step each one needed: 1. [Pointing Pair](https://sudokuflow.com/lessons/pointingPair/) 59.6% 2. [Naked Pair](https://sudokuflow.com/lessons/nakedPair/) 18.3% 3. [Box/Line Reduction](https://sudokuflow.com/lessons/boxLineReduction/) 13.1% 4. [Hidden Pair](https://sudokuflow.com/lessons/hiddenPair/) 6.0% 5. [Pointing Triple](https://sudokuflow.com/lessons/pointingTriple/) 2.2% 6. [Naked Triple](https://sudokuflow.com/lessons/nakedTriple/) 0.8% 7. [Hidden Triple](https://sudokuflow.com/lessons/hiddenTriple/) 0.1% [What each Sudoku difficulty level asks of you →](https://sudokuflow.com/data/sudoku-difficulty-levels/) ## How to solve Hard Sudoku What makes a puzzle Hard is the hardest step it needs. Most often that step is Pointing Pair (60%), Naked Pair (18%), Box/Line Reduction (13%), or Hidden Pair (6%). Hard is where notes start to pay. Pencil in the candidates, then look for a number whose candidates in one box all sit in a single row or column: that number can then be removed from the rest of that row or column. Pairs and triples of candidates work in a similar way. [Learn Pointing Pair step by step →](https://sudokuflow.com/lessons/pointingPair/) ## Hard Sudoku: questions and answers ### How many numbers do Hard puzzles start with? Every Hard puzzle here starts with 31 of the 81 squares filled in. ### Do Hard puzzles need guessing? No. Every puzzle has exactly one solution, and the hint engine of our app solves each one with logic alone, one technique at a time. ### Can I get a hint while I play? Yes. Hint names the technique the next step needs and shows it on your board one step at a time, with the same hint engine our app uses. ### What comes after Hard? One level up, Expert puzzles are most often decided by Skyscraper. ## All six levels - [Easy Sudoku](https://sudokuflow.com/play/easy/) Nearly Complete (95%) - [Medium Sudoku](https://sudokuflow.com/play/medium/) Hidden Single (100%) - **Hard Sudoku** Pointing Pair (60%), Naked Pair (18%), Box/Line Reduction (13%), or Hidden Pair (6%) - [Expert Sudoku](https://sudokuflow.com/play/expert/) Skyscraper (55%), Y-Wing (30%), or Empty Rectangle (6%) - [Master Sudoku](https://sudokuflow.com/play/master/) XY-Chain (59%), W-Wing (28%), X-Chain (6%), or XYZ-Wing (5%) - [Extreme Sudoku](https://sudokuflow.com/play/extreme/) ALS-XZ (86%) or Unique Rectangle (12%) ## More Sudoku to play - [Print Hard Sudoku](https://sudokuflow.com/printables/sudoku/hard/) - [Daily Sudoku: four new puzzles every day](https://sudokuflow.com/daily/) - [Sudoku checker](https://sudokuflow.com/tools/sudoku-checker/) - [Sudoku for kids](https://sudokuflow.com/printables/kids/) ![Sudoku app icon](https://sudokuflow.com/assets/app-icon.png) ## Want more boards like this? We also make a Sudoku app for iPhone, iPad, Mac and Android. There are no ads in it at all, it works offline, and when you ask for a hint it shows you the technique instead of just filling in a number. [App Store iPhone, iPad, Mac](https://apps.apple.com/app/apple-store/id6502922368?pt=125379530&ct=sudokuflow_web&mt=8) [Google Play Android](https://play.google.com/store/apps/details?id=com.rubigogames.sudoku&referrer=utm_source%3Dsudokuflow%26utm_medium%3Dweb%26utm_campaign%3Dsite) Sudoku Flow is made by Rubigo Games, the developer of the Sudoku app recommended on this site.