🕵️ Logic Grid Detective
Read the clues, mark the grid and work out who has what. One answer, every time.
How to play
- Pick your rank and a case. Stars open the higher ranks.
- Each friend has a different one of each thing. Read all the clues first.
- Tap a square once for ✗ (no), again for ✓ (yes), and again to clear it.
- A ✓ fills in the ✗ marks for the rest of its row and column.
- Tap a clue to cross it off when you've used it.
- When every friend has a ✓, press Check my answer. Use a hint if you're stuck.
Free logic grid puzzles online
Logic Grid Detective is a free game of logic grid puzzles, also known as logic problems, deduction puzzles or Einstein puzzles. You get a small group of friends, a short list of clues and a grid to fill in. Who owns the rabbit? Who came by train? By crossing out what can't be true, you work out what must be true. Every case has exactly one answer and never needs a guess. It plays in your browser with no download, and each case can be printed.
What is a logic grid puzzle?
A logic grid puzzle gives you several groups of things, such as names and pets, and tells you that each item in one group goes with exactly one item in the other. The clues never tell you everything directly. Instead, you draw a grid, with names along one side and pets along the other, and mark each square with a cross for no or a tick for yes. As the crosses build up, the answers appear. This type of puzzle has been popular in puzzle magazines for decades, and a similar puzzle known as the Zebra Puzzle is often said to have been invented by Albert Einstein, though there's no evidence for that.
How to solve logic grid puzzles
Start with the certain clues. Anything that says someone has something gets a tick straight away, and that rules out the rest of the row and column. Then add the no clues. "Zoe doesn't own the cat" is a simple cross. Look for the last empty square: if a row has a cross in every square but one, that one must be a tick. Link the grids. On harder cases, a clue may connect two things without saying who, such as "the rabbit's owner brought the pizza". Mark that in the third grid, and when you find out who owns the rabbit, you also know who brought the pizza. Go back through the clues. A clue that didn't help at first often helps later, so keep rereading until the grid is full.
Logic puzzles for kids
Most logic puzzles are written for adults, so kids can find them hard to start. This game is built to teach. The Cadet rank has only three friends and one thing to work out, which suits children from about seven. Constable adds a second category and a second grid. Sleuth and Chief Inspector step up to four and five friends, which is a real challenge for teens and adults. The clues use simple words and familiar things like pets, snacks and sports, so children can focus on the thinking. Stars open each new rank as they build their skills.
Why logic puzzles are good for you
Solving these puzzles is good practice for deductive reasoning, in which you start from facts and work out what must follow. It builds patience, careful reading and the habit of checking your own reasoning. These are skills that show up in math, science and computer programming, and in many tests. Teachers often use logic grids to practise reading closely, because a single word like "not" can change everything.
Print a case for class
Press the Print button during a case to get a clean page with the story, the clues and blank grids. It's free to use at home or in the classroom, and it's a handy way to run a whole-class detective challenge. Try letting pairs of students work together and explain each step out loud. You can find the answer by solving the same case in the game.
Stars and ranks
Each of the 48 cases can earn up to 3 stars: one for solving it, two for solving it without a wrong check, and three for doing that with no hints too. Your stars and solved cases are saved on your own device, and you can replay any case to improve your score.
A worked example
Say three friends, Maya, Leo and Zoe, each have a different pet: a cat, a dog or a rabbit. The clues are: "Maya doesn't own the dog", "Leo doesn't own the cat" and "Zoe owns the rabbit". Start with the sure thing and put a tick where Zoe meets the rabbit. That tick rules out Zoe for the cat and the dog, and it rules out Maya and Leo for the rabbit. Now look at Maya: she can't have the rabbit, and the first clue says she doesn't have the dog, so she must have the cat. That leaves the dog for Leo, and the second clue agrees. You never had to guess, and every step followed from the one before. All the cases in this game work like that, however big the grid gets.
Logic puzzles in the classroom
Logic grids fit well into reading and math lessons alike. Start as a whole class with a Cadet case on the board, and ask students to explain each mark they suggest. Then let pairs try a Constable case together, taking turns to read a clue and decide what it tells them. Encourage them to cross off each clue as they use it, and to say out loud what's certain and what's only possible, because that difference is the heart of logical reasoning. For extension work, students can write their own case: choose the answer first, and then write clues that lead to it. It's harder than it looks, and they'll quickly discover why every clue has to count.
More logic and brain games
If you like deduction, try Battleship Solitaire, Number Nine or the coded messages in Cryptogram. Every puzzle is on the Brain Games page.
Free and safe
Logic Grid Detective is free to play, with no download, no sign-up and nothing to buy. There is no chat, and your progress is saved only on your own device. See the Parents & Safety page for more.
Frequently asked questions
What is a logic grid puzzle?
It's a puzzle where you match items from different groups using clues. You mark a grid with crosses and ticks until only one answer is possible.
How do you solve a logic grid puzzle?
Mark the clues you are sure of first. A tick rules out the rest of its row and column, and when only one square is left in a line, it must be a tick. Keep rereading the clues as the grid fills up.
Do these puzzles ever need guessing?
No. Every case has exactly one solution, and you can reach it using only the clues.
Are these logic puzzles good for kids?
Yes. The Cadet rank is designed for children from about seven, with just three friends and one category. Higher ranks suit older children and adults.
Can I print the puzzles?
Yes. Press the Print button during a case for a page with the story, clues and blank grids.
Is Logic Grid Detective free?
Yes. It is free to play in the browser with no download, no account and nothing to buy.