Einstein's Riddle: The Zebra Puzzle, Solved, and the Myths Around It

What Einstein's riddle is

Einstein's riddle is a logic-grid puzzle. Five houses stand in a row. Each has a different color, an occupant of a different nationality, a different pet, a different drink and a different brand of cigarettes. Fifteen clues tie the attributes together. Two items are never mentioned, water and a zebra, and the question asks who has them.

Each attribute can be arranged across five houses in 120 ways, so the raw search space is 120 to the fifth power: 24,883,200,000 combinations. The clues cut that to exactly one. Computer scientists call the format a constraint satisfaction problem, and the puzzle has served as a benchmark for constraint solvers since at least Patrick Prosser's 1993 paper. In 2025 the ZebraLogic study turned the same format on large language models; see our guide to ChatGPT's IQ for what such benchmarks do and do not show.

Where it came from: Life International, 1962

The earliest known printing ran in Life International on December 17, 1962. The magazine published the solution on March 25, 1963, along with the names of several hundred readers who had solved it.

The 1962 text gives no author. Later retellings attached two famous names, Albert Einstein and Lewis Carroll, and the Einstein label stuck. The clues have also been rewritten many times, which is why versions found online rarely match one another clue for clue. The answers below apply to the 1962 original.

Two myths: Einstein, and the 2 percent

Einstein did not write it, as far as any record shows. Wikipedia's article on the puzzle and American Mensa reach the same verdict: there is no known evidence for his authorship, or for Carroll's. The reference site Math Lair agrees on Einstein. Math Lair notes that the earliest sources, from the 1960s and 1970s, say nothing about Einstein. American Mensa points out that the 1962 version names Kools, a cigarette brand that did not exist during Carroll's lifetime or Einstein's boyhood. Einstein, born in 1879, was a boy in the 1880s and 1890s; Kools did not appear until the 1930s.

The 2 percent figure is unsourced. The claim usually reads "98 percent of the world cannot solve it" or "only 2 percent can." Nobody who repeats it names a study, a sample, a time limit or a scoring rule, and a percentage without those things is not a measurement. Math Lair says flatly that there is no truth to it and that a person who thinks logically, with patience and time, should be able to solve the puzzle. The number has the same shape as other viral IQ claims, a round figure attached to a famous name. Our guide to Einstein's IQ takes apart a similar case.

The puzzle, in our own words

Here is the 1962 puzzle, reworded. As in the original, "right" means your right.

1. Five houses stand in a row, each with its own color, nationality, pet, drink and cigarette brand.
2. The Englishman's house is red.
3. The dog belongs to the Spaniard.
4. Whoever lives in the green house drinks coffee.
5. The Ukrainian's drink is tea.
6. The green house stands immediately to the right of the ivory house.
7. The man who smokes Old Golds keeps snails.
8. The resident of the yellow house smokes Kools.
9. The man in the middle house drinks milk.
10. The Norwegian occupies the leftmost house.
11. The Chesterfield smoker's next-door neighbor owns the fox.
12. The horse lives next door to the Kools smoker.
13. Orange juice is the drink of the Lucky Strike smoker.
14. The Japanese man smokes Parliaments.
15. The blue house stands beside the Norwegian's.

Question: Who drinks water, and who owns the zebra? Try it with a pencil before reading on.

How to solve it: anchor, eliminate, branch

Draw a grid with five columns for the houses and five rows for the attributes. Then work in three moves.

• Anchor. Fill every cell a clue fixes outright. Clue 10 puts the Norwegian in house 1. Clue 15 makes house 2 blue. Clue 9 puts milk in house 3.
• Eliminate. Cross out what each anchor forbids. The ivory-green pair from clue 6 cannot touch blue house 2, and green cannot be house 3, because green drinks coffee and house 3 drinks milk. The pair sits in houses 3-4 or 4-5. House 1 is then neither red (the Englishman is not Norwegian) nor blue, green or ivory, so it is yellow. Clue 8 gives it Kools; clue 12 puts the horse in house 2.
• Branch. When the clues run dry, test one case to a contradiction. Here the branch is the position of the green house.

The full solution

Test green in house 4. Then house 3 is ivory and house 5 is red, home to the Englishman. The Ukrainian, who drinks tea, must live in house 2. House 1 smokes Kools, so it cannot hold the orange juice of the Lucky Strike smoker; house 1 drinks water and house 5 orange juice. The Ukrainian in house 2 cannot smoke Old Golds, because Old Golds go with snails and house 2 has the horse, so he smokes Chesterfields. Old Golds then fall to whichever of houses 3 and 4 is not the Japanese man's, and that house belongs to the Spaniard, who owns the dog, not snails. Contradiction.

So green is house 5. House 4 is ivory, house 3 red with the Englishman, and house 5 drinks coffee. House 1 again drinks water. If the Ukrainian lived in house 4, orange juice and Lucky Strikes would land in house 2, which could then belong only to the Spaniard, whose dog clashes with the horse. So the Ukrainian is in house 2, orange juice and Lucky Strikes in house 4, the Spaniard and his dog in house 4, and the Japanese man in house 5. House 2 smokes Chesterfields, house 3 Old Golds with the snails, the fox goes to house 1, and the zebra is left for house 5.

Ten practice puzzles with worked answers

Items 1 to 6 are original grids written for this page; our Python solver confirmed each has exactly one solution. Items 7 to 10 walk back through the Zebra Puzzle.

1. Three houses. Ada, Ben and Cal live in houses 1 to 3, left to right, and drink tea, coffee or juice. Ada lives in neither end house. Cal lives to the right of Ben. Ben drinks tea. The coffee drinker lives directly left of the juice drinker. Who drinks juice?
   Answer: Cal. Ada is in house 2, so Ben is in 1 and Cal in 3. Tea goes to house 1, leaving coffee in 2 and juice in 3.
2. The race. Ray, Sam, Tia and Uma run a race with no ties. Sam beat Tia but lost to Uma. Ray finished directly behind Uma. Give the order.
   Answer: Uma, Ray, Sam, Tia. Uma must finish ahead of Sam, Sam ahead of Tia, and Ray right behind Uma. That chain needs four places in a row starting with Uma, so Uma won.
3. Three scientists. Rhee, Soto and Tan study stars, cells or rocks and own a cat, a dog or a parrot. Rhee neither studies rocks nor owns the parrot. The cell biologist owns the dog. Soto studies stars. Tan owns the cat. Match them.
   Answer: Rhee: cells, dog. Soto: stars, parrot. Tan: rocks, cat. With Soto on stars and Rhee off rocks, Rhee studies cells and so owns the dog.
4. Four seats. Dana, Eli, Fay and Gus sit in seats 1 to 4 and play piano, violin, cello or flute. Gus sits in seat 1 and does not play the flute. The pianist sits at an end. Eli sits directly right of the violinist. Fay plays cello in an even-numbered seat. The flutist sits next to Fay. Who plays what?
   Answer: Gus piano, Dana violin, Eli flute, Fay cello, in seats 1 to 4. If Fay sat in seat 2, the flute would take seat 3 and the violin would land in seat 1 or seat 4, and either way Eli could not sit directly to its right. So Fay is in seat 4, the flute in seat 3, the piano with Gus in seat 1 and the violin in seat 2.
5. Four floors. Ines, Jon, Kai and Lea live on floors 1 to 4 (bottom to top). Their fields are math, physics, chess and music; their drinks are tea, cocoa, water and espresso. The chess player lives on top and drinks water. The musician lives on floor 1, and it is not Jon. Kai lives directly above the mathematician. Ines drinks espresso. The physicist drinks tea. Lea lives directly below Ines. Cocoa is drunk below tea.
   Answer: Floor 1 Lea, music, cocoa; floor 2 Ines, math, espresso; floor 3 Kai, physics, tea; floor 4 Jon, chess, water. Math and physics share floors 2 and 3. Physics on floor 2 would force cocoa to floor 1, Ines and her espresso to floor 3, Kai to floor 4 and Jon to the music floor, which the clues forbid. So physics is on floor 3, Kai with it, and Ines can only be on floor 2 above Lea.
6. Five houses, mini zebra. Mira, Noah, Omar, Pia and Quinn each play one sport (tennis, rowing, fencing, judo, golf) and eat one fruit (apple, banana, cherry, fig, grape). Noah lives in house 1. The golfer lives in the middle house, and it is Quinn. Mira fences. The rower lives next to the fencer. Pia lives directly right of the fig eater. The judo player lives next to Noah and eats bananas. The grape eater lives in house 5. Omar eats apples. Who rows, and who eats cherries?
   Answer: Omar rows; Quinn eats cherries. The judo player next to Noah must be in house 2 with the bananas, so Omar's apple can only sit in house 4, so Mira fences in house 5 with grapes, Pia takes house 2 with judo and bananas, the fig goes to house 1, and the rower must be house 4.
7. Zebra checkpoint. Using clues 10 and 15 only, what color is house 2?
   Answer: Blue. The Norwegian is in house 1, which has one neighbor.
8. Zebra checkpoint. Why can the green house not be house 3?
   Answer: Green drinks coffee (clue 4), but house 3 drinks milk (clue 9).
9. Zebra checkpoint. Who drinks water?
   Answer: The Norwegian, in the yellow house.
10. Zebra checkpoint. Who owns the zebra?
    Answer: The Japanese man, in the green house.

What the riddle does and does not measure

The puzzle exercises deduction, the ability to hold several constraints in mind and the discipline to test a case to its end. Those skills overlap with the reasoning sections of intelligence tests. It is still not an IQ test. It has never been normed on a population, it has no time limit, and once solved it cannot be solved fresh again. Nobody can say that cracking it signals an IQ of 130 or any other number.

Practice raises familiarity with a format, not intelligence. For a broader workout, try our IQ test questions with answers, the abstract reasoning test guide and the probability trap in the Monty Hall problem. Our free IQ test is a practice screener, not a clinical score. More in our IQ guides.

Editorial standard: IQ figures for historical figures are retrospective estimates and are labeled as such; scores for living people appear only when the person disclosed them or a reputable outlet reported them. Corrections: contact the editors.