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EnglishWhat Is the Killer Sudoku Calculator on Stillgrid?
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The Killer Sudoku Calculator is a helper page on Stillgrid, a mobile-first sudoku site, for working out the number combinations that can fill a Killer Sudoku cage. It is a calculation aid, not a solver: you use it to check which sets of digits fit a cage's sum and size, then place those digits on the grid yourself. It is most useful when a cage is large or its sum is unusual, and least necessary for small two- or three-cell cages you can work out mentally.
What the tool is for
Killer Sudoku adds cages to the standard grid. Each cage is a group of cells marked with a total, and the digits inside must add up to that total while still obeying normal sudoku rules (no repeats in a row, column, or box). The hard part is often arithmetic rather than logic: which digits can sum to, say, 23 across five cells without repeating?
The calculator answers that question. You give it the cage's sum and the number of cells, and it returns the digit combinations that satisfy both. From there you eliminate options using the rest of the grid.
Where it sits on Stillgrid
Stillgrid describes itself as "sudoku, the quiet way" and offers several variants: Classic, Killer, Jigsaw, and X-Sudoku, plus a daily sudoku, an archive, a difficulty grader, and an Evil Sudoku section. The Killer Sudoku Calculator sits alongside these as a supporting page for the Killer variant rather than as a separate game.
That means the natural workflow is: open Killer Sudoku to play, and keep the calculator available in another tab or return to it when a cage stalls you. The site requires JavaScript to play, so the calculator and the puzzles both depend on it being enabled.
How to use it in practice
- Identify the cage. Note its total and how many cells it covers. For example, a three-cell cage summing to 7.
- Enter those two values into the calculator.
- Read the returned combinations. For a three-cell cage summing to 7, the possible digit sets are limited, which immediately narrows what each cell can hold.
- Cross-check against the grid. Remove any combination that repeats a digit already placed in the same row, column, or box, or that conflicts with a neighbouring cage.
- Repeat as cages resolve. As digits get placed, earlier combinations drop away, and the remaining options often force a single answer.
When it helps most, and when to skip it
| Situation | Use the calculator? | Why |
|---|---|---|
| Large cage with a high or low sum | Yes | The number of combinations is hard to enumerate by hand |
| Cage spanning a row, column, or box boundary | Yes | Fewer constraints are visible at a glance |
| Two-cell cage | Usually no | The pairs are quick to recall |
| Late in the puzzle with most digits placed | Rarely | Remaining options are already few |
A useful habit is to treat the calculator as a check rather than a crutch: work out your candidate combinations first, then confirm them. That keeps the solving logic yours and uses the tool only to catch arithmetic slips.
Practical notes
- The calculator handles the combination arithmetic; it does not read your grid or suggest placements, so the deduction stays with you.
- Because Stillgrid is mobile-first, the page is usable on a phone, which suits playing Killer Sudoku on the same device.
- The site's other aids, such as the difficulty grader, are separate pages; the calculator is specific to Killer cages.
- No account is needed to use the site, per its description of being a no-signup sudoku site.
If you are new to the variant, start with a Classic puzzle to learn the grid, then move to Killer and keep the calculator open for the first few cages until the combination patterns become familiar.