---
title: "Sudoku Solver with Step-by-Step Hints | PuzzleBirch"
description: "Type or paste a sudoku to solve it at once, or get one hint at a time with the technique named and explained. Spots mistakes and double answers."
url: https://puzzlebirch.me/sudoku-solver/
---

[PuzzleBirch](https://puzzlebirch.me/) · Solver

# Sudoku solver with hints

Type in the puzzle you are stuck on. Ask for one hint at a time, with the technique named and explained, or solve the whole grid at once.

## How the solver and hints work

Enter the puzzle by clicking a square and typing, or paste all 81 squares at once: digits for the givens and 0, a dot or a dash for the blanks. Grids copied from books and websites usually paste straight in, lines and all.

**Hint** looks for the next digit a person could find by reasoning, never by guessing. It starts with the simplest ideas: a *hidden single* (in a row, column or box, a digit has only one square left) and a *naked single* (a square has only one digit left). When those run out it tries pointing pairs, naked and hidden pairs and triples, X-wings, XY-wings and a few more, and tells you each step it took. The new digit appears in red, with its row, column or box shaded.

**Solve** fills in the rest with a fast search, and **Check** tells you whether the digits so far can still lead to a solution. Mistakes are caught early: a digit repeated in a row, column or box turns red, and a grid with no solution, or with more than one, says so before any hint is given.

## Questions

**Can it solve every sudoku?**

Yes. Solve uses a search that finishes even the hardest known puzzles in a fraction of a second. Hints are limited to techniques a person would use, so on extremely hard grids they can run out; the solver then says so and offers to reveal a square.

**What does “more than one solution” mean?**

A proper sudoku has exactly one answer. If a given digit was missed or mistyped, several grids can fit, and no amount of logic can choose between them. Check the puzzle against the original.

**How is the difficulty worked out?**

By the hardest technique needed when always taking the simplest step available: singles only is Easy, pairs and pointing is Medium, X-wings and XY-wings are Hard, and chains such as the skyscraper are Expert.