Scales use bioelectrical impedance to measure body fat percentage. They have an accuracy of +/- 5 points of the actual reading. Meaning the value is 1-5 points

Scales use bioelectrical impedance to measure body fat percentage. They have an accuracy of +/- 5 points of the actual reading. Meaning the value is 1-5 points higher or lower than the real value, so a reading of 6% on the scale could mean a real value of 1%-11% (not 5.7%-6.3%).