This value depends on where in the world you are. There is always 12 hours of daylight at the equator. As you move away from the equator to the poles, the intensity and duration of light can change...
Has to do with the earths tilt and whether you live in the northern or southern hemisphere.
The amount of daylight on the day of the summer solstice ranges from 12 hours at the equator to 24 hours between the pole and the (ant)arctic circle.
14.1
The Winter Solstice has 8 hours of daylight.