Do you mean on the scales at a doctor's office?

I don't think there is such a thing, short of something so expensive that it's out of the question for even the wealthiest individuals, as a scale that's 100% accurate.

BUT. If we weigh ourselves, over and over, on a hard flat surface with the same scale, we'll eventually see whether the trend, based on that scale, is up, down or steady.

That's one of the reasons why how our clothes fit, and whether or not we need larger or smaller clothes is really a better measure of our progress than the scale, at times.