How to Solve Logic Grid Puzzles Step by Step
Here's how to solve logic grid puzzles: turn every clue into X marks for the pairings that are impossible, put a dot or tick wherever only one box is left in a row or column, then cross that dot out along its row and column and carry it into the other grids. Repeat until the grid is full. The worked example below takes you through a whole puzzle, one clue at a time.
If you keep losing track of what you've already ruled out, IQ Tester checks whether that's working memory, logic chains or scattered attention, and trains the one that's yours: Find my weak spots.
How a logic grid works
What is a logic grid puzzle? It's a puzzle where several people (or things) each match exactly one item from a few categories, and clues let you work out every match.
For example: three friends each own a different pet and play a different sport. Who owns what, and who plays what?
How to read a logic grid
The grid is really a few small tables stuck together:
- People × Pets: does Priya own the cat? Yes or no.
- People × Sports: does Priya play tennis?
- Pets × Sports: does the cat owner play tennis?
Each small table has one "yes" per row and one per column, because every person has exactly one pet, and every pet belongs to exactly one person.
The symbols
| Mark | Meaning |
|---|---|
| X | Definitely not a match |
| ● (dot or tick) | Definitely a match |
| Blank | Not known yet |
That's the X-and-dot method. It sounds simple because it is. The skill is in using it consistently.
Mark every no first
When you first read the clues, don't hunt for the answer. Go through every clue and put in all the X marks it gives you.
Clues give you no's in a few common shapes:
- "Priya doesn't own the cat." → X at Priya/cat.
- "The dog owner swims." → the dog goes with swimming, so X the dog against every other sport, and X swimming against every other pet.
- "Tom doesn't swim." → X at Tom/swimming.
- "Either Tom or Zoe owns the dog." → X Priya/dog.
Why no's come first
Positive facts are rare in the clue list. Negative facts are everywhere. Marking them all early sets up the moment when a row suddenly has only one blank left.
When only one box is left
This is the core rule of logic grid puzzles: if a row or column has only one blank left, that blank is the answer.
Every person has exactly one pet. So if Priya's row in People × Pets has X under cat and X under dog, Priya must own the fish. Put a dot there.
Then clean up
Once you place a dot:
- X the rest of that row (Priya can't own anything else).
- X the rest of that column (nobody else owns the fish).
Those new X's often leave another row with one blank. Chains like this are how grids fall apart quickly.
Cross-grid deductions
This is the step most beginners miss, and it's why they get stuck on medium puzzles. Information moves between the small tables.
The transfer rule
If Priya owns the fish (a dot in People × Pets), then whatever you know about the fish owner, you know about Priya, and the other way round.
- Fish owner does not play soccer? → Priya does not play soccer.
- Priya plays tennis? → the fish owner plays tennis.
A quick check habit
Every time you place a dot, ask: "What do I know about the other half of this pair in the other grids?" Copy it across. Then look for new one-blank rows.
This is the point where many people's grids go wrong: a mark gets missed in one table, and three moves later nothing adds up. Keeping everything in mind across three grids is a working memory job, and it's hard to tell from inside whether that's your weak spot or whether you're rushing. IQ Tester's 16-question check pins that down in about two minutes, then gives you daily drills like "Chunk it" aimed at it. Find my weak spots
A full worked example
Let's do one completely. Grab a pencil and draw a 3×3 grid for People × Pets, one for People × Sports and one for Pets × Sports.
The puzzle. Priya, Tom and Zoe each own one pet (cat, dog, fish) and each play one sport (tennis, soccer, swimming).
Clues:
- Priya doesn't own the cat or the dog.
- The dog owner swims.
- Tom doesn't swim.
- Priya doesn't play soccer.
Step 1: Mark the no's
- Clue 1: X Priya/cat, X Priya/dog.
- Clue 2: dot dog/swimming. X dog/tennis, X dog/soccer, X cat/swimming, X fish/swimming.
- Clue 3: X Tom/swimming.
- Clue 4: X Priya/soccer.
Step 2: One box left
Priya's pet row has X for cat and dog. Only fish is left. Priya owns the fish. Put a dot, and X Tom/fish and Zoe/fish.
Step 3: Cross-grid deduction
We know the fish owner doesn't swim (from clue 2's X's). Priya owns the fish, so X Priya/swimming.
Now Priya's sport row has X for soccer and swimming. Only tennis is left. Priya plays tennis. X Tom/tennis and Zoe/tennis.
Step 4: Keep chaining
Tom's sport row: X swimming (clue 3), X tennis (step 3). Only soccer left. Tom plays soccer. That leaves Zoe swimming.
The dog owner swims (clue 2), and Zoe is the swimmer, so Zoe owns the dog. Only the cat is left for Tom: Tom owns the cat.
Answer
| Person | Pet | Sport |
|---|---|---|
| Priya | fish | tennis |
| Tom | cat | soccer |
| Zoe | dog | swimming |
Check against every clue
- Priya has the fish, not the cat or dog. ✅
- Zoe owns the dog and swims. ✅
- Tom plays soccer. ✅
- Priya plays tennis. ✅
Always do this final check. It takes 20 seconds and catches the mistakes you'd otherwise hand in.
Hard puzzles: try a case
On hard logic grid puzzles, you'll eventually hit a point where every row has two or more blanks and no clue gives you anything new. That's when you try a case.
How to solve hard logic grid puzzles with a case
- Find a row with exactly two blanks. Say Zoe owns either the bird or the rabbit.
- Assume one, in pencil or a different colour: Zoe owns the bird.
- Follow the chain of X's and dots from that assumption.
- If you hit a contradiction (a row full of X's, or two dots in one row), the assumption was wrong. Zoe owns the rabbit. Erase the test marks and put that in.
- If no contradiction appears, don't trust it yet. Undo and test the other option too.
Clue shapes to learn for bigger puzzles
- "Either/or" clues: "The swimmer is either Tom or the cat owner." This also tells you Tom isn't the cat owner.
- Order clues: "Zoe finished two places after the soccer player." Rules out the last two places for the soccer player.
- Neither/nor clues: "Neither Tom nor the dog owner plays tennis." Tom isn't the dog owner, and neither plays tennis.
If you want to build the wider skills behind these (chaining, testing cases, knights-and-knaves), see how to get better at logic puzzles. And for daily drills that train the same thinking outside puzzles, read how to improve logical reasoning skills.
Train the skill behind every logic grid puzzle
You now know how to solve logic grid puzzles: mark the no's, fill the last box, carry facts across grids, and test a case when you're stuck. In the next two minutes, IQ Tester's 16 questions show whether logic chains, working memory or scattered attention is what trips you up, and then you get one tip and a ten-minute drill every day, with logic, pattern, number and verbal problems weighted toward your weak spots.
FAQ
How do you solve a logic grid puzzle for beginners?
Draw the grid, go through each clue and put an X on every pairing it rules out, then look for any row or column with just one blank left. That blank is a match. Mark it, X out the rest of its row and column, and repeat.
What is the X-and-dot method in logic grids?
X means "definitely not" and a dot (or tick) means "definitely yes." You fill in X's from the clues, and when a row has only one open box, you put a dot there. It's the standard way to keep track of your deductions.
How do I get better at logic grid puzzles?
Start with 3×3 puzzles, always mark every no before looking for yes, and practise cross-grid deductions every time you place a dot. Checking every clue at the end teaches you where your mistakes happen.
How do you solve hard logic grid puzzles when you're stuck?
Reread each clue with what you now know, then find a row with only two options and test one as a case. If it creates a contradiction, the other option is correct.
Is a zebra or Einstein puzzle the same as a logic grid puzzle?
They're close cousins. Zebra and Einstein puzzles use the same kind of clues and can be solved with a logic grid, but they're usually larger, with five people and five categories.