How can the range of an aircraft be calculated given real wind conditions?
The best answer: Use the charts in the respective Pilot's Operating Handbook (POH). There you should find correction factors for the parameters which influence aircraft range


Fuel on board: The more, the better. But note that doubling fuel will not double range.
Take-off mass: If you take no payload, the aircraft will produce less induced drag and reach a slightly higher range. See the chart below for an example.
Wind enroute. Follow the link; the wind component parallel to your flight direction will change the range by the product of wind speed times flight time.
Cruise altitude: This depends on the type of engines, jets benefit more from altitude than propeller aircraft.
Temperature


Generally, there should be a chart like this:



It plots the maximum achievable range over the aircraft's payload and assumes that the tanks are filled such that the flight starts with the maximum take-off mass. The chart should also have an explanation that clarifies which altitude and which thrust setting were used.

Or you use approximations like Breguet's range equation, which require detailed knowledge of the aircrafts L/D and the engine's fuel consumption. That will be the weakest point of any range calculation: Sufficient data how changes in the aforementioned parameters affect the result.