From Longman Dictionary of Contemporary Englishby a mileby a mileinformal by a very large amount He was the best player on the pitch by a mile. → mile
Examples from the Corpus
by a mile• It's the best by miles.• Whoever planted that tree beat Mr Buddy by a mile.• But the service is not yet good enough by a mile.• They're the favourites by a mile.• At the rate he was going we were going to miss it by a mile.• And yet Simeon flunked virtually every exam, often by a mile.• Some writers have suggested that this will replace browsing, but they miss the point by a mile.• I hope you pay heed, you're still my favourite tome by miles ... for now. 