🔎 How to solve a logic grid puzzle, step by step
Here is the method that solves any logic grid puzzle, a full example solved step by step, and how to see an explained solution for every puzzle on the site.
The method: six ways to reason
1. Direct clues
A clue like “Emma has the cat” is an instant ✓, and “Liam is not 8” is an instant ✗. Start with these.
2. One ✓ in every row and column
Every kid has exactly one pet. Once there is a ✓, the rest of the row and column get ✗. And when one empty cell is left in a row, that is the ✓.
3. Linking the grids
If Emma has the cat, everything you know about the cat is true for Emma too: if the kid with the cat is not 9, Emma is not 9 either.
4. Order clues
“Noah is younger than Mia” means Noah is not the oldest and Mia is not the youngest. “Right after” and “next to” narrow things down even more. Also: Noah and Mia are two different kids.
5. Either… or…
“Either Zoe ate pizza, or Zoe arrived at 12:30 (but not both)”: once one part turns out false, the other one is certainly true.
6. Assume and find a contradiction
In hard puzzles: assume a ✓ in a cell and keep reasoning. If you reach something impossible (like a row with no free cell), the cell is ✗.
Example: try it yourself first
This is an easy puzzle with 5 clues. Solve it on the board, then compare with the full solution below.
The full solution, step by step
This is how to solve the example. Steps where you only mark ✗ in the rest of a row after a ✓ are left out: the board does that for you.
- Henry has the rabbit.
- Either the kid who has the rabbit is 9 years old, or that kid is 7 years old.
- The kid who has the parrot is exactly one year older than Liam.
- Ava is exactly one year older than the kid who has the goldfish.
- The kid who has the parrot is older than Henry.
Show the solution steps
- Clue 1 says it directly: Henry has the rabbit.
- By clue 2 only two options are left, so the kid who has the rabbit is not 6 years old and the kid who has the rabbit is not 8 years old.
- Clue 3 talks about two different kids, so Liam does not have the parrot.
- Clue 4 talks about two different kids, so Ava does not have the goldfish.
- Clue 5 talks about two different kids, so Henry does not have the parrot.
- We know that Henry has the rabbit, and also that the kid who has the rabbit is not 6 years old, so Henry is not 6 years old.
- We know that Henry has the rabbit, and also that the kid who has the rabbit is not 8 years old, so Henry is not 8 years old.
- By clue 3, Liam is not 9 years old: otherwise there would be no option left for the kid who has the parrot.
- By clue 3, the kid who has the parrot is not 6 years old: otherwise there would be no option left for Liam.
- By clue 4, the kid who has the goldfish is not 9 years old: otherwise there would be no option left for Ava.
- By clue 4, Ava is not 6 years old: otherwise there would be no option left for the kid who has the goldfish.
- By clue 5, Henry is not 9 years old: otherwise there would be no option left for the kid who has the parrot.
- Every other option has been ruled out, and only one is left: Henry is 7 years old.
- We know that Henry has the rabbit, and also that Henry is 7 years old, so the kid who has the rabbit is 7 years old.
- By clue 3, Liam is not 6 years old: otherwise there would be no option left for the kid who has the parrot.
- Every other option has been ruled out, and only one is left: Liam is 8 years old.
- Every other option has been ruled out, and only one is left: Noah is 6 years old.
- Every other option has been ruled out, and only one is left: Ava is 9 years old.
- We know that Noah is 6 years old, and also that the 6-year-old does not have the parrot, so Noah does not have the parrot.
- Every other option has been ruled out, and only one is left: Ava has the parrot.
- We know that Ava has the parrot, and also that Ava is not 8 years old, so the kid who has the parrot is not 8 years old.
- Every other option has been ruled out, and only one is left: the kid who has the parrot is 9 years old.
- By clue 4, the kid who has the goldfish is not 6 years old: otherwise there would be no option left for Ava.
- Every other option has been ruled out, and only one is left: the kid who has the goldfish is 8 years old.
- Every other option has been ruled out, and only one is left: the 6-year-old has the hamster.
- We know that Noah is 6 years old, and also that the 6-year-old has the hamster, so Noah has the hamster.
- Every other option has been ruled out, and only one is left: Liam has the goldfish.
The answer
| Kid | Pet | Age |
|---|---|---|
| Ava | parrot | 9 |
| Noah | hamster | 6 |
| Liam | goldfish | 8 |
| Henry | rabbit | 7 |
The secret of solving a logic grid puzzle is order. Go through all the clues once and mark what they say directly. Then use the most important rule, one ✓ in every row and column, and link the grids. Only then go back to the order clues and the either/or clues, which usually crack the puzzle open.
On every puzzle on the site, the Hint button does not just reveal a cell: it writes which clue or rule leads to the next step. That way you learn the method while you play. And the Solution button shows the whole path, like the example above.
Questions and answers
Where can I see the solution of a puzzle?
Every puzzle on the site has a Solution button: it fills the grids, shows the answer table and explains step by step how to get there. The printable puzzles have an answer page for each puzzle.
What do I do when I get stuck?
Go over the clues again, especially the before/after and either/or clues, which can give more than one mark. Then look for a ✓ in one grid and carry the information to the other grids. Still stuck? The Hint button explains the next step.
Is guessing allowed?
Better not. Hard puzzles have an advanced step that looks like guessing, “suppose that… and see what happens”, but it is a proof: if the assumption leads to a contradiction, it is false.
Why does every clue matter?
Because the puzzles here have no extra clues: the computer removes every clue the puzzle can do without. If you finished and a clue is left unused, check again.