Quote Originally Posted by Steve Smith View Post
It does work if you use the ratio of the areas of the print rather than the enlarger height squared (although that will get you to a good starting point for further experimentation).

It almost works. When you change the enlarger height, you have to refocus. This changes the effective aperture number, and therefore the required exposure. Dials and charts have been published over many decades to let us get the precise exposure after changing enlarger height without metering or test strips. A google search should point to some of them.