It needs to fit with the rest of your windows. From the outside, if the proportions of this window are different than the others it won't look right. If this is an addition, show us a picture of the side of the house it's going to be on. If it's a new home build, there should be an architect involved who would be the best person to answer this question, but maybe you can show us an elevation of that side of the house from the set of plans.

Thank you so much for your reply! It's the only window on that wall except for a picture window that is only 26x41. The architect plans say 48 inches for bathroom so both windows start at about 42 inches high on that same wall.

Who knows no where near enough info lets see the exterior elevation for that wall and honestly a 26 x41 picture window is barely the size of a small picture . Why on erth 114' ceiling ina bathroom anyway maybe in one 2x the size but this will look like a tunnel

The bathroom is being built in the family room which has 114" ceilings. I can drop the ceiling if necessary but the architect said 114" is only 6" higher than new construction homes so I figure I would leave it at 114"

The small picture window I mentioned is only at the end of a small hallway which leads to the bathroom.

If the window is on an exterior wall it needs to be similar size, or header height to balance. If the header height needs to be different it still needs to look like it belongs and not placed haphazardly.

Completely agree! The 48 inch bathroom window allows for both windows on that exterior wall to fall at 26 inches from ceiling. The picture window will have built ins below it on the interior wall so it will start at a higher elevation than the bathroom window allowing both to have same header.
Just got nervous that 48 inch window would look too short with tall ceiling in bathroom.