169 Fair and square

(PW) honest, honestly

I won the contest fair and square.

(free) adj.        

fair and honest; just. Opposite of unfair.

fair-and-square - just and honest

fair, just - free from favoritism or self-interest or bias or deception; conforming with established standards or rules; "a fair referee"; "fair deal"; "on a fair footing"; "a fair fight"; "by fair means or foul"

(usingEnglish)
If someone wins something fair and square, they follow the rules and win conclusively.

(phraseFinder) Honest and straightforward, especially of business dealings.

Origin

In the 16th century 'square' meant 'fair and honest' so 'fair and square' is tautological.

George Puttenham used that meaning of square in The arte of English poesie, 1589:

"[Aristotle] termeth a constant minded man - a square man."

Francis Bacon's essay Of Prophecies, 1604 is the first known use of 'fair and square':

"Faire, and square. The gamester calls fooles holy-day."