A dotted quarter note is equal to three beats when the time signature is 4/4. In a 4/4 time signature, there are four beats per measure, and a quarter note receives one beat. When a quarter note is dotted, its duration is increased by one-half of its original value. Therefore, a dotted quarter note is equal to one beat (original value) plus one-half of a beat (half of its original value). Hence, a dotted quarter note is equal to three beats in a 4/4 time signature.
