One thing to be familiar with which can blur the ratio is business class ‘lite’ fares offered by the likes of Finnair and copyright. Use air miles or loyalty points: Quite a few Airways give the choice to employ air miles or loyalty factors to update to business class. https://businessflightshop.co.uk/blog/get-your-first-class-tickets-to-new-york-some-destinations-for-christmas-holiday-vacations/