Actually, most of the weighing scales are accurate as they are capable of measuring even a tenth of a gram. If you want to check the accuracy of your weighing scale, use the pennies as they weigh 2.5 grams each. Turn the weighing machine on, make sure the initial weight displaying is zero and place a penny on the scale. Mark the weight and add 2 more pennies, noting the weight in between each. The weights have to be doubled by each penny placement. For example, 2.5g, 5g and 7g. If the weight is off, then accuracy of that machine is likely inaccurate.