Logic Grid Puzzles

Logic grids look daunting the first time you see one. Rows of categories, columns of items, a matrix of empty cells, and a list of clues that seem to talk about completely different things. It's actually simpler than it looks. Every logic grid puzzle is solvable — the clues always contain enough information to pin down exactly one answer, and there's a reliable process for extracting it.

Read everything first

Resist the urge to start marking the grid after the first clue. Read all of them. Seriously. Some clues reference things you won't understand until you've seen the full set, and your brain is better at finding connections when it has the complete picture.

On a second pass, sort the clues mentally into three buckets: direct matches ("Eve drinks coffee"), direct eliminations ("Frank is not the doctor"), and conditional links ("the tea drinker plays soccer"). Start with the first bucket, then the second, then tackle the conditionals once the grid has some marks in it.

Direct assignments

"Alice is the doctor." That's a checkmark in the Alice/Doctor cell and an X in every other cell in that row and column. One mark produces up to 2×(N−1) eliminations, where N is the number of items per category. On a 5×5 grid, a single checkmark eliminates 8 other cells. These cascade fast.

Some clues bundle two assignments together: "Alice is a doctor who lives in London." That's three marks — Alice/Doctor, Alice/London, and Doctor/London — plus all their eliminations. Clues like these are gold. Find them first.

Elimination

"Bob does not own the cat." Mark an X. Not as exciting as a checkmark, but eliminations compound. After enough X marks in a row or column, only one cell remains open, and that cell becomes a forced match. This is where most of the actual solving happens — not from the clues that hand you answers, but from the ones that slowly wall off every wrong option.

Cross-referencing between grids

This is the technique that separates beginners from everyone else. If you know Alice = Red and Red = Cat, then Alice = Cat. The connection flows through the shared category. Any time you place a checkmark, check whether that match lets you propagate information to a different sub-grid.

It works with eliminations too. If Alice = Red and Red ≠ Dog, then Alice ≠ Dog. Our grid does some of this automatically, but it can't chain everything. You'll need to spot multi-step propagations yourself, especially on harder puzzles.

Hidden singles

When only one empty cell remains in a row or column of a sub-grid, it must be a match. This happens constantly after a wave of eliminations. The grid fills itself once you've placed enough X marks — you just need to scan for rows and columns that have narrowed down to one option.

Our interface handles this automatically. When you mark a match and the resulting eliminations leave a single possibility somewhere, the grid fills it in and propagates further. Watching the cascade is one of the more satisfying parts of the experience.

Conditional chains

"The tea drinker plays soccer." You don't know who drinks tea yet, so you can't place this directly. But once you figure out who the tea drinker is, this clue instantly gives you their sport. Conditional clues are deferred information — they sit inert until a prerequisite is solved, then fire all at once.

On harder puzzles, you'll chain conditionals: "The tea drinker plays soccer" plus "the soccer player lives in Paris" means the tea drinker lives in Paris. You can build these chains before knowing who the tea drinker is, and that narrowed profile might eliminate enough options to identify them.

When you're stuck

Go back to the clues you skipped. Conditionals you passed over on the first round often become usable after a few more cells are filled. Re-read every clue and check whether the current grid state makes any of them actionable.

If that doesn't help, look for indirect eliminations. Check each empty cell and ask: "If this were true, would it create a contradiction?" If placing a checkmark in a cell forces two items in another sub-grid to share the same match, that cell must be an X. This is trial-and-error, but it's structured trial-and-error — and it's how the hardest logic grids are actually solved.

What each level asks of you

• Easy — 3 categories, 3 items each. Direct assignments and basic elimination. The grid is small enough that you can brute-force it mentally, but try using the proper techniques as practice.
• Medium — 4×4. Conditionals become necessary. You'll need to cross-reference between at least two sub-grids to finish.
• Hard — 4 categories, 5 items. More items per category means more cells and longer elimination chains. Multi-step cross-referencing required throughout.
• Expert — 5×5. Ten sub-grids to manage. Every technique in this guide comes into play, and conditional chains can be 3-4 steps deep.
• Einstein — 5×5 with fewer clues than expert. Minimal information, maximum deduction. Named for Einstein's riddle, which is possibly the most famous logic grid puzzle ever written.

Quick tips

• Process direct assignments before anything else. They produce the most eliminations per clue.
• Re-read all clues after each batch of marks. Clues that were useless before might now apply.
• On 5×5 puzzles, keep track of which sub-grids you've checked recently. It's easy to miss a hidden single in a grid you haven't looked at in a while.
• If two categories have a known match (Alice = Red), immediately check what you know about Red in other sub-grids and copy it to Alice.