High cost, low accuracy, dependence on lighting, high error rate, intrusion of privacy and size of the devices are some of the disadvantages of using biometrics. The disadvantages depend on which of the different biometric identification methods is used by an identification device.
Facial recognition uses a 2-D recognition system, which is susceptible to changes in lighting, the person’s hair, whether the person wears glasses and age, as people's faces change over time. In order for facial recognition to be accurate, the image of user's face must be lit evenly and preferably from the front, which is not always possible and can be very hard to do in some environments.
Voice recognition has low accuracy, and a voice can be easily recorded and used for unauthorized access. An illness such as a cold can alter the user's voice and make identification more difficult or even impossible.
Retinal scanning is an expensive identification method and can cause delays, as the comparison with stored templates can take up to 10 seconds.
Fingerprint reading can make mistakes with the dryness or dirt of the finger’s skin, as well as with age. Fingerprints are captured in an image format that requires a lot of memory to process.