A Major 6th is equivalent to moving up six degrees in the major scale, starting from the tonic.
By themselves, Major 6ths tend to have a positive, hopeful sound.
A Major Sixth is equivalent to 9 semitones.
Because a Major Sixth is a large interval, it is recommended to anchor off a nearby interval, rather than counting through all six steps in the major scale.
Always locate a Perfect Fifth, then go up a whole step.