We recommend Google Flights to find this deal because it has an easy-to-use calendar tool to browse dates and fares. See an example itinerary by pressing the blue button below.
Select one of the date boxes to expand the calendar view and see fares for each departure date. The fares shown will update if you pick a longer or shorter trip - trying different lengths can reveal more options.
You can find the cheapest fares with Online Travel Agents in step two, but you can book with the airline through Google Flights if you prefer.
Find on Google Flights