Scales are scales. They are not absolute divine weight measurements. The Association of Mad Dieters doesn't come around and calibrate the scales in doctors offices or gym to be the correct.
At the gym and doctor's office, if you're using the standard doctor's office scale, make sure it's balanced before you step onto it. Most nurse's will do this for you but the one at my gym is always off. If it's off at your gym, move that little screw on the side until it's balanced.
Jennasmom - I'm not sure if you're dancing or what on your scale.
If you scale is *that* tempramental, you might need a larger one. Jkfla is right, stand straight up - quit moving.
The most accurate scale (I know of) is going to be at a big shipping place. That scale is the size of a small platform and they're meant to weight cargo. They are calibrated all the time to ensure correct postage. Yeah, I'm not weighing myself in front of any strangers either.
Any weight watchers employees know if they have professionally calibrated scales?
My advice. Use a tape measure.