Intervals in musical notes

Just like there are other measuring units for different quantities like kg for mass, meter for length etc etc, there is also a way to measure the relative pitch or distance between two notes in music. The quantity that we measure between two notes is called the interval. The shortest interval is the minor second interval. On guitar this is the distance between two notes adjacent to each other i.e. just one fret apart and is called a half step. So B and C are a minor second apart or just one fret apart or a half step apart. Unlike in other measuring units, we generally do not use terms like 2 minor second intervals or three minor second intervals like we do 1 kg, 2 kg 3 kg etc.

Each interval has got a name. Here is the list and the corresponding distance in terms of no. of half steps or no. of frets on guitar.

Unison-(zero distance ex- C to C)
Minor second-(Half step ex-C to C#)
Major second-(2 Half steps or a full step ex-C  to D)
Minor third-(3 half steps ex- C to D#)
Major third-(4 half steps ex-C to E)
Perfect fourth-(5 half steps ex- C to F)
Augmented fourth-(6 half steps ex-C to F#)
Perfect fifth-(7 half steps ex- C to G)
Minor sixth-(8 half steps ex- C to G#)
Major sixth-(9 half steps ex- C to A)
Minor seventh-(10 half steps ex-C to A#)
Major seventh-(11 half steps ex- C to B)
Octave-(12 half steps ex-C to C)

Here in the examples, the first reference C note is the lowest in pitch. Hence while counting make sure that you are counting towards high pitched notes.