If your home shower is within a bathtub, you will want to fit your shower valve at a height of two feet and four inches (You might want to Pick The Right Curtain For Your Shower).
This measurement is a lot lower than if your shower was in its own stall. The reason is that the valve is also tasked with connecting the bath tap and the shower.
Another consideration is that when you take your relaxing end-of-day bath (that you have oh-so earnt), you don’t want to be struggling to reach the valve, you want it to be easy.
The tub spout needs to measure four inches higher than the tub’s top edge. What this will do is create a two-inch gap over your bathtub’s overflow rim.
Of course, if you are raising an army of giants, this is what we would consider special circumstances, but for most families of average height, four feet is the money number.