Tenor banjos are tuned in fifths, much like the violin, viola, and cello. Remember that C, G, D, and A are the strings of the tenor banjo, meaning it is tuned exactly one fifth below a violin. If you have ever tuned a violin, the method for tuning the tenor banjo will not be new to you and you may be able to do it by ear. If you are not familiar with tuning in fifths, give yourself some time and practice and you will be a pro in no time.
Choose an electric tuner to make sure you tune the strings to exactly the right pitch. If you are new to music, it is easier to tune an instrument if you have a device to guide you while your ear develops. It is also much easier to learn a new piece if you know that you are hitting the right notes. Many banjo players choose reliable electric tuners made by Korg or Boss.
Set the electric tuner to A440 to make sure that the tuner detects the proper pitch for your tenor banjo. Many tuners have multiple pitch settings, so this is something to be careful of.
Pluck the A string of your tenor banjo and notice where your tuner's needle goes. When the A string is in tune, the needle will be smack dab in the middle of the letter A on your tuner. If the needle is to the left of the A, slowly and carefully tighten your tenor banjo's A string, being careful not to snap the string by tightening too much. If the needle is to the right of the A, slowly loosen the string until you reach the correct pitch.
Proceed to the D string using the same technique used for tuning the A string. Once the D string is tuned, strum the A and D strings together. You should hear a perfect fifth. To double check your tuning and the fret positioning on your tenor banjo, place your finger on the seventh fret of the D string and strum it together with the A string. The notes should match.
Tune the G and C strings using the same methods used for tuning the D and A strings. First, get the strings in tune with the tuner and then check the tuning against the other strings by using the seventh fret. Once you have finished tuning the C string, your tenor banjo should be perfectly in tune and ready for you to play.
If your strings are old or your pegs need adjusting, the strings of your tenor banjo may continually go flat. If this happens, see your nearest repair shop for help in selecting new strings or tending to your pegs.