Dear Sir/Madam Thanks for writing us here, Please note, FOBO Bike/Tire 2 sensors doesn't need to calibrate because they have tested many times and certified that FOBO sensors accuracy are - 0.94 PSI to +0.94 PSI however If you want to compare FOBO Bike 2 sensor reading and the handheld gauge, you need to take both device accuracy into account. In this case FOBO Bike 2 sensor is more accurate. We would appreciate it if you could share more details of the incident you are facing by writing an email to "cx@my-fobo.com", That will definitely help us to investigate the issue and provide you a better user experience. We look forward to serving you better.  Best Regards Amir Bayati Customer Experience | Salutica Allied Solutions Sdn. Bhd. (a subsidiary of Salutica Berhad) 3 Jalan Zarib 6, Kawasan Perindustrian Zarib, 31500 Lahat, Ipoh, Perak, Malaysia M  +6016 787 3175 | my-fobo.salutica.com.my