“Piece of cake” means something is very easy to do, and the phrase is usually traced to 20th-century English. The earliest clear print example is often credited to Ogden Nash in 1936, and many sources think it was later reinforced by older “easy” expressions like “cakewalk” and “easy as pie”.

Origin

A common explanation is that the phrase grew out of the idea that cake is enjoyable and easy to eat, so a simple task could be compared to getting or eating a piece of cake. Another influential theory links it to “cakewalk,” a dance contest in which the prize was a cake, which made “cake” itself a symbol of an easy win.

What we know

The history is not perfectly settled. Different dictionaries and language guides point to slightly different paths, but they agree on the core meaning: a piece of cake is something effortless. The phrase was already in use by the 1930s, and British wartime usage helped spread it further.

Simple example

  • “Don’t worry about the quiz — it’s a piece of cake.”
  • Meaning: “It’s very easy.”

Bottom line

The safest answer is that the idiom became popular in the early 1900s, probably through a mix of dessert imagery, older “easy” sayings, and wartime slang, rather than from one single proven source.