Determine if you would like to buy a balance beam scale or a bathroom scale. Balance beam scales, also known as physician's scales or doctor's scales, are upright and take up more room than a bathroom scale, although they tend to be more accurate. If you would like the most accurate scale available, purchase a balance beam scale.

Try the scales out in person. There is no way to tell if a scale is accurate or calibrated correctly when you order it online. Even if you're sure what brand you would like to buy, test the scale you are planning to purchase in person before buying it.

Go to the doctor's office to get weighed by a professional. Ask for your exact weight and write it down. Wearing the same clothing you wore at the doctor's office, try out scales to see if the readouts match the weight you received at the doctor's office.

Test the scale. Stand on the scale with your feet slightly apart and wait several seconds. If you are testing a bathroom scale, make note of the weight reading. If you are using a balance beam scale, slide the 100 pound weight bar one notch to the left until the scale falls to the right, then move the bar one notch to the left. Slide the 1 pound weight bar gently until the scale is suspended exactly center. Make note of the weight reading.

Weight yourself three to five times on the same scale, making note of any weight discrepancies from your original number. An accurate scale should read the same weight every time, provided you are wearing the same clothing.

Determine if the scale is calibrated correctly. Bathroom scales with a dial readout are calibrated if the dial points at "zero" when no weight is on the scale. If the dial points above or below zero, the scale is not calibrated correctly.