Home scales can't be. That is more for the tall slide type dr scales.

The best way to calibrate a home scale is to use weights or something that you know for sure is a certain poundage.

The scale should have a small knob that should zero it out.

You can test the low end of the scale by piling on some 1lb canned foods. Most elelctronic scales won't get off at different weight levels like a slide scale can.

If all else fails, calibrate to your dr's numbers.