To design an airplane wing we first have to estimate it's size (area). Wing Calculator will calculate a minimium area for a wing (or it can reverse calculate the stalling speed). The area is connected to the apility of the plane to create lift. At the cruise speed the plane usually needs only a fraction of the maximum lift since the cruise speed and conditions are such that the lift could easily be created with a smaller wing also.
Usually the lift during landing is critical since the plane is flying slowly and using all it's wings lifting capacity to fly as slow as possible (this is used here). An other extrem might be if the plane should fly very high. Thin air needs lot of lift to keep the plane flying. An additional extrem might be the wing's ability to create G forces during pull. Here are some maximum pull values for different categories aircraft:
Positive +4.4 G's +6.0 G's
Negative -1.76 G's -3.0 G's
We have to remember that normal people do not stand much more than 4 G's without anti-g trousers and suits.
The Wing Calculator uses the selected maximum lift devices to estimate the wing's CLmax and given landing (minimium) speed to calculate the required wing area. Normally you have to be able to fly at least 61 knots during landing. Many small planes can fly slower than that, especially if partially loaded. Usually the maximum weight (cross weight) is used at sea level (0 ft).