It also can be influenced by how continuous you want the border to be, if you have fittings that you want to be above or below (or not on) the line, how low the windowsill is.
Nowt definite to say. My bathroom was done with 200x250 (WxH) tiles, two above the bath (i.e. four in total from the floor), tile border then five to the ceiling which looks good. In that particular room there was nothing to define a border level (no wall window). I'm just doing Mum's bathroom now, same size tiles, split 4-border-6, where the border is to run below the window cill at about 1m from floor level. I have a feeling this might look a bit low, but the shower control is now plastered into the wall (lined up to expected grout lines) and I ain't moving it again!
When I was planning my bathroom and en suite I was going to make the split at 1m above floor level, which coincided with the window ledge in the en suite so it (the split) went a bit higher, which turned out to be half way and it looks ok.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.