Pick your sudoku.
The classic 9x9 below, or a gentler set built for kids. Both are free, single-solution verified, and print with an answer key.
Classic sudoku generator.
Easy is singles-only. Medium needs locked candidates. Hard forces an XY-Wing-class move. Expert needs chains — the evil tier. Answer key and large print are one click each.
Every puzzle is checked for a single unique solution before it prints. Difficulty is graded by the hardest human technique the puzzle actually requires — not by clue count. No signup, no email, no watermark.
How to solve sudoku.
Hunt for cells with a single legal digit, and for digits that fit only one cell in a row, column, or box. Easy puzzles are nothing but this step — no pencil marks needed.
Lightly note every still-possible digit in each empty cell. The rest of the solve is just crossing candidates off as you learn more.
If a digit inside a 3x3 box can only sit in one row or column of that box, it cannot appear in that same row or column anywhere else — erase it there. This is the workhorse of medium puzzles.
Two cells in a unit that share the exact same two candidates lock those digits to themselves — remove them from the rest of the unit. Hidden pairs and triples are the same idea in reverse.
Hard puzzles need an X-Wing, XY-Wing, or Swordfish — a pattern spanning several units that kills one candidate. Expert puzzles chain a few of these together; take notes and work in pencil.
Sudoku FAQ.
Do these puzzles have exactly one solution?
Yes — every puzzle is checked by a solution-counting solver before it is drawn, and any grid with more than one solution is discarded. A puzzle with two answers is a broken puzzle; you will not get one here.
How is the difficulty decided?
By the hardest human technique the puzzle actually requires, not by how many numbers are given. Easy needs only single-candidate logic; medium needs locked candidates; hard forces an X-Wing / XY-Wing-class move; expert requires chained reasoning. That is why a 'hard' here is genuinely hard.
What is the difference between Hard and Expert?
Hard is still fully solvable by a known advanced technique (XY-Wing, X-Wing, Swordfish). Expert cannot be cracked by those alone — it needs chains or trial-and-error, which is the 'evil' tier most sites reserve for veterans.
Can I print the same puzzle again later?
Each puzzle carries a stable id (a difficulty letter plus a seed, e.g. H-734102) printed under the grid. The generator is deterministic, so the simplest way to reprint is to keep the PDF — the file itself never changes.
Is there an answer key?
Yes. Leave 'Include answer key' checked and the matching solutions print after the puzzle pages, each labeled with the same id as its puzzle so they are easy to pair.
Is there a large-print option?
Yes — the large-print toggle enlarges the digits and prints one or two puzzles per page, which is easier on the eyes and good for classrooms, care homes, and low-vision solvers.
Do I need an account or special software?
No. It runs entirely in your browser, the PDF opens in any reader, and it is free with no signup, no email, and no watermark. Print as many as you like.