How a logic grid puzzle works
You are given four people and three categories — a drink, a pet and a city — with four possible values in each. Every value is used exactly once, so the puzzle is really three simultaneous matchings. The clues never tell you the answer directly; they narrow it. The satisfaction comes from the moment a negative clue you had ignored suddenly forces a positive one, and the whole grid collapses into place in four or five moves.
How these puzzles are made
A solution is chosen at random, then every clue that happens to be true of it is generated — positives, negatives and links that mention no name at all. Clues are added one at a time, checking after each against all 13,824 possible arrangements, until exactly one survives. Then every clue is tested for redundancy and removed if the puzzle still resolves without it. What you see is therefore minimal: take any clue away and the puzzle becomes ambiguous.
The order to work in
- Direct clues first. "Jonas drinks water" is free information — write it in.
- Then negatives on nearly full rows. A category with three values placed is solved by elimination.
- Link clues last. "Whoever drinks tea lives in Oslo" is useless until you know who drinks tea, and decisive the moment you do.
- Propagate every placement. One certainty rules out three others in the same category.
- Never guess. If nothing follows, you have missed a clue rather than run out of information.
Why link clues feel harder than they are
A clue like "the cat owner lives in Cairo" names nobody, so it feels unusable. In fact it is two facts in one: it tells you that whoever has the cat is in Cairo, and it tells you that the cat owner is not in Lisbon, Oslo or Tokyo. Written into the grid as three eliminations rather than one relationship, link clues stop being mysterious and become the most productive lines in the puzzle.
What this exercises
| Skill | Where it shows |
|---|---|
| Systematic elimination | Ruling out three values every time you place one |
| Working memory | Holding two half-solved categories at once |
| Deductive chaining | Following a link clue through to a second placement |
| Patience | Not guessing when the next step is not visible yet |
Where to go next
If you enjoy the strict-deduction part, the deductive reasoning test gives you premises and asks which conclusion must follow, and the syllogisms test does the same with the belief-bias traps built in. For the pattern-finding side rather than the elimination side, try the untimed matrix test.
Frequently asked questions
What is a logic grid puzzle?
A set of clues about several people and their attributes, where exactly one combination fits every clue. You work it out by elimination rather than by guessing.
Is there always one answer?
Yes. Every puzzle here is checked against all 13,824 possible arrangements before it is shown, and only puzzles with exactly one surviving arrangement are used.
How do I start a logic grid puzzle?
Begin with the direct clues that name a person and a value, fill those in, then use the negative clues to eliminate. Link clues that mention no name are usually the last pieces to fall.
Do the puzzles repeat?
No. Each puzzle is generated from a fresh seed when you start, so the names, values and clues differ every time.
Are logic grid puzzles good for your brain?
They exercise systematic elimination and working memory, and people get noticeably better with practice. Whether that improvement carries over to unrelated tasks is doubtful.
Are these logic puzzles free?
Yes, completely free with no account and no email, and you can generate as many new puzzles as you like.