Nootropics Depot Milligram Scale | NDS-201

The terms accuracy, precision, capacity, and resolution are important concepts when talking about the properties of a scale. Although the terms have distinct meanings, many times people confuse them with one another. When an object is placed on a scale, the scale responds by displaying a measurement of that object's weight. The confidence in knowing how close the displayed weight is to the actual weight depends entirely on the accuracy, precision, and resolution of the scale at a given weight. Let's look at each one individually.

The resolution of a scale is the smallest increment in measured weight that can be displayed on the scale. The NDS-201 is a milligram scale. Therefore, the smallest unit the scale can display is 1mg. This is also the amount the scale increments or decrements by when weighing. The NDS-201 cannot measure fractions of a milligram. To measure fractions of a milligram, you would need to move to a 0.1mg or 0.01mg precision balance, and those run into the thousands of dollars per scale.

The accuracy of a scale is how close the value of an object's displayed weight is to the object's actual weight. If a scale indicates that a 10 gram weight weighs 10.005 or 9.995, then the scale is accurate to within 0.05% at 10 grams, or a 5mg deviation. This is the maximum amount the scale would deviate from the actual weight value of an object at that specific weight. This accuracy of a scale is different at various weights as well. This is due to the resolution of the scale affecting how close it can get the displayed weight to the actual weight of an object. Since a milligram scale has a 1mg resolution, and you cannot display fractions of a milligram, the accuracy of the displayed weight will be lower at lower weight values. Let's say we are measuring 50mg instead of 10 grams. If we wanted an accuracy of 0.05% at 50mg, the scale would need to have a resolution of 0.001mg, or one microgram. This is an incredibly tight tolerance, and microgram scales run tens of thousands of dollars to achieve that resolution. So that accuracy level is impossible at the 50mg level on a milligram scale. If you weigh a 50mg weight and get a value of 48mg or 52mg, then your scale is accurate to within 4% at 50mg, or a 2mg deviation. What this means from a practical standpoint is that your milligram scale gets more accurate the more weight you put on it.

The precision of a scale is the measure of repeatability of an object's displayed weight for multiple weighings of the same object. Essentially, precision is the deviation or fluctuation of the measured weight of a single object across multiple instances of weighing on the same scale. If you weigh a 10 gram object 5 times, and you get 10.005, 10.001, 9.995, 9.999, and 10.000, your precision is 0.05%. This is because the maximum value of deviation (5 milligrams) from the average of all the weights (10 grams) is 0.05%. Think of precision as a measure of how much a scale's weight display will fluctuate from one time to the next.

Finally, capacity is the largest weight the scale is capable of weighing. The NDS-201 has a capacity of 20 grams. This means that the maximum weight of an object you can put onto the scale is 20g. Not only is that the maximum it can accurately weigh, but it can also damage the mechanism of the scale by going over that maximum capacity.