Some combined time and distance flight calculators, such as at AirplaneManager.com, include wind speed in calculations to determine estimated flight time. Distance-only flight calculators do not include wind speed as they measure only distance, which wind does not alter.
The flight time and distance calculator at AirplaneManger.com allows the wind speed to be set at a five-day average, a seasonal average, a live estimate or none. Other flight time calculators, such as at TravelMath.com, do not include an adjustable wind speed function. TravelMath.com notes that wind speeds affect the time of routes, so incoming and outgoing flights between the same two locations can differ.