Both 'favorable' and 'favourable' are correct spellings of the same word, with 'favorable' being the American English spelling and 'favourable' being the British English spelling. The choice between the two depends on the English variant you are using.

Favor and favour are two spellings of the same noun or verb. The spelling depends on the type of English. In American English, you use “favor.” In British English, you use “favour.” Canadian English mainly follows British English guidelines, so favour is the correct spelling.