How accurate are the counterweight scales typically found in Drs office?

[Marvin_the_Martian]

@Machine_Elf

A slope of 2% is typical for garage floors, but that’s not the magnitude of the resulting measurement error.

The normal force measured by the scale varies with the cosine of the slope angle. A 1:48 slope is 1.19 degrees, the cosine of which is 0.99978. So a scale placed on a sloped garage floor would be expected to read low (due to said slope) by 0.0217%

Yeah, tried to do it on my head using small angle approximation but hosed it up real good.