What is the difference between a personal scale from the supermarket and a seca scale?
Both, for example, have the same number scale with a 1 kg gradation. The difference is that the seca scale displays the exact weight it measures. The scale from the supermarket shows the weight which only loosely corresponds to the actual weight. The supermarket scale is not very accurate. By the way, that applies to both mechanical and electronic scales.
Definition of accuracy acc. to DIN EN 60051
The accuracy of a scale is the degree of agreement between the displayed and correct value. It is determined by the intrinsic error limits and influencing effect limits. In other words, accuracy depends on the quality of the components, the quality of the load cell and environmental conditions. An environmental condition that affects accuracy can be the temperature or humidity. Under error limits for calibrated scales is understood the permissible tolerance, i.e. the permitted weight deviation by plus and minus. They are load sensitive and defined in the calibration regulations.
Definition of gradation
Gradation is the smallest possible readable distance between to weight values. For digital scales, it is identical to readability. For mechanical scales, it is the smallest weight value on a scale consisting of dividing lines and numbers that are read with a pointer or index.