in (an amount of time) flat

in (an amount of time) flat

In only the amount of time specified. Used to describe an action that was done extremely quickly. The thieves broke into the store, emptied the register, and were out again in five minutes flat. Once I had the feeling for how the articles needed to be structured, I was able to write them in an hour flat.
See also: amount, flat, of

in two minutes, ten seconds, etc. ˈflat

(informal) used to say that something happened or was done very quickly, in no more than the time stated: He tidied his room in ten minutes flat.She spent nine months writing the first half of the book and then finished it in three months flat.
See also: flat, ten, two