Kakuro solver
Enter the clues and get the answer. If the grid has more than one answer, this says so rather than picking one and calling it done.
What this tells you that others do not
Most solvers return an answer. This one returns the number of answers, capped at two, and that difference matters more in Kakuro than almost anywhere else.
If you are checking a puzzle from a book or a newspaper and it turns out to have two answers, the puzzle is broken and no amount of further solving will fix it. If you are setting a grid of your own, that count is the only thing standing between a puzzle and an embarrassment.
And if you are stuck on a grid you believe in, knowing there is exactly one answer is itself useful information — it means the deduction is there to be found and you have not been sent on an impossible errand.
Setting a grid of your own
It is much harder than it looks, and the trap is not the one people expect. Making the arithmetic work is easy; making the answer unique is not, because ambiguity is the default state of a Kakuro grid rather than an occasional accident.
The reliable method is to fill the whole grid with digits first, read the clues off the runs, and then check the count. If it comes back as more than one, change a digit somewhere the two answers disagree — that is precisely where the ambiguity lives — and check again.
That is the same loop this site uses to build its own puzzles, and it converges surprisingly fast. What does not work is adding more clues, because in Kakuro every clue is already forced by the digits; there is nothing to add.
How it works
It narrows each run to the writings its clue still allows given the squares crossing it, repeats until nothing changes, and then — only if it has to — takes the most constrained square and tries each remaining digit.
The narrowing step includes a matching check that a simpler solver would skip: it is not enough that every digit of a writing is available somewhere in the run, each digit has to be placeable in a different square. Without that the solver wanders down branches that cannot exist.
It runs in your browser. Nothing is uploaded, nothing is stored, and the code doing it is the same module that generated every puzzle on this site.
Common questions
- Can this solver tell me if my Kakuro has two answers?
- Yes, and that is the main thing it is for. It counts answers and stops at two, so it distinguishes a sound puzzle from a broken one instead of returning whichever answer it found first.
- Is my grid sent to a server?
- No. The solver runs entirely in your browser using the same module that built the puzzles on this site. Nothing leaves the page.
- How do I make my own Kakuro puzzle?
- Fill every square with digits first and read the clues off the runs, then count the answers. If there is more than one, change a digit where the answers disagree and count again.
Check this before you rely on it. This tool is provided free and without warranty, and its results are not professional advice.