Free King-Size Killer Sudoku puzzles with cage sum constraints. Daily challenge updated every day — plus 25 downloadable PDFs across five difficulty levels.
Two ways to play: solve today's challenge or download a PDF to print and solve at your own pace.
A new 16×16 Killer Sudoku every day. View today's puzzle image, track your time with the built-in timer, download the PDF, or browse the full archive of past puzzles.
Open Daily Puzzle →25 printable King-Size Killer Sudoku PDFs organised across five difficulty tiers. Filter by difficulty and download instantly — no account required.
Browse Downloads →Killer Sudoku combines standard Sudoku rules with an extra layer of arithmetic constraints. The grid is divided into cages — groups of cells outlined with dashed borders. Each cage shows a target sum in the top-left corner. The digits inside the cage must add up to that target, and no digit may repeat within a cage.
On a 16×16 grid, these constraints interact across 256 cells using symbols 1 through 16. Each row, column, and 4×4 box must contain every digit from 1 to 16 exactly once — and every cage must hit its target sum. The result is one of the most logically demanding puzzle formats available.
Start by identifying cages with limited digit combinations. A 2-cell cage with sum 3 must be {1,2}. A 3-cell cage with sum 6 must be {1,2,3}. Use these forced sets to eliminate candidates from intersecting rows, columns, and boxes. As more cells resolve, cage constraints cascade into powerful deductions — especially when multiple cages share a unit.
In the 16×16 format, the "Rule of 136" (the sum of any complete row, column, or box is 136) becomes a powerful technique: calculate the sum of all cages fully inside a row or column to find which cells "stick out" as innies or outies.
More prefilled cells. Straightforward cage combinations. Good for learning the 16×16 format.
Fewer givens. Requires basic Killer techniques like cage-sum elimination.
Innies & outies, multi-cage interactions. Expect 60–90 minute solves.
Advanced strategy chains. Only for experienced Killer Sudoku solvers.
Maximum constraint density. These puzzles will test even the most seasoned experts.