Everyone knows that a weighing device has a maximum capacity limit where the device will stop indicating weight. If your kitchen scale has a 1 kg capacity, would you consider weighing a large watermelon on it? Of course not, but did you know that all weighing devices also have a minimum, or lower, limit? Any measurement below this minimum limit cannot be trusted to be accurate. For example, would you lend your kitchen scale to your pharmacist to weigh out your next prescription? Probably not, because these items are usually very light, resulting in an inaccurate weighing on the kitchen scale; thus a medication produced this way could be lifethreatening. If you are going to buy a balance or scale, or you already have the device, it is important that you understand the “sweet spot” or range where the device gives the most accurate results. Since most weighing manufacturers do not declare this lower limit, it is important to understand the implications.
One method to determine this lower limit is to consult references such as weights and measures where they have attempted to approximate this value by multiplying the device’s readability by a fixed value. However, this method doesn’t take into account the device’s actual performance. The device could be better or much worse.
The purpose of this weighing guide is to explain the Safe Weighing Range which lies between a scientifically calculated lower limit, determined through calibration, and the maximum limit (capacity) of a balance or scale.