False acceptance rate (FAR)
How often a biometric system wrongly accepts an imposter as a match.
The false acceptance rate, or FAR, is the proportion of times a biometric system wrongly accepts an imposter as a genuine match. It is a core accuracy measure, paired with the false rejection rate, which is how often it wrongly rejects the real person.
There is a trade-off between the two: tightening the threshold to reduce false acceptances tends to increase false rejections. The right balance depends on whether the priority is security or convenience.
