Hello, according to your question, the newly bought blood pressure monitor should have been calibrated at the factory, and does not need to be calibrated, if there is a deviation, it should belong to the quality problem, and you can deal with the seller or manufacturer. It is recommended that blood pressure monitors for home use should be calibrated once a year to ensure the accuracy of the blood pressure measured. All medical instruments should be calibrated regularly, including blood pressure monitors. Hospitals do regular calibration of medical instruments to ensure its accuracy. Electronic blood pressure monitors for home use can usually be calibrated at the place of purchase. There are also some patients who will bring their own blood pressure monitors to outpatient clinics. When the blood pressure is measured with the hospital's blood pressure monitors, they will immediately use the blood pressure monitors they brought with them to measure their blood pressure, and take the blood pressure value measured by the doctor as a reference to calibrate their electronic blood pressure monitors.