To ensure that your weighing scales or balances are weighing correctly we recommend that they are checked with calibrated weights on a daily, weekly or monthly basis depending on how important the measurement is to your product or process and what the implications would be if the weighing equipment was out of tolerance.
You will probably have a weighing company calibrating and certifying your weighing equipment six monthly or annually but this only ensures that the scales are correct at the time of certification and if the weighing results are important to you then we recommend additional checks to ensure that any damage or a fault has not caused a calibration error. Even a poorly fitting protective cover can cause significant weighing errors that are not obvious without checking with calibrated weights.
We have compiled a how to choose calibration weights
guide if you would like further information.