The only way to ensure accurate and precise solution delivery is by regularly checking each pipette on the analytical balance. High quality and consistent results depend on a skilled operator properly using well maintained equipment. This video will cover the procedure for calibrating a micropipette, as well as the proficiency test used to determine if the user is pipetting correctly. Calibration of a micropipette officially means determining the difference between the dispensed volume and the selected volume. This can tested by weighing the volume of distilled deionized water pipetted onto a sufficiently sensitive analytical balance. New users will be asked to perform pipette calibration as a proficiency test in order to demonstrate that they are able to use a micropipette correctly, and with sufficient accuracy. The Mettler AE240 analytical balance will be used because it has sufficient sensitivity to measure dispensed volumes accurately and precisely from all micropipettes. If needed, review video on proper use of the analytical balance before proceeding.