Viola sizes refer to the actual length of the instrument's body, in inches. The largest common size is 16.5". Adults generally play a 15.5" to 16.5" viola.
Violas are larger than violins, and are measured to be a little bit over-sized for the player. That said, it is important that the student is comfortable holding and playing the instrument or physical problems may develop.
Please note that this information is provided as a free service and without warranty or liability. There are different methods of sizing a viola, so if your teacher has a recommendation, you should follow your teacher's advice.
Stand with your left arm fully extended, perpendicular to your body. Measure from the neck to the base of your fingers.
Note that this results in a higher measurement than the recommended method for sizing the violin (neck to mid-palm).
The chart below shows the comfortable ranges for each viola size. For example, if your arm measurement (see above) is 24.5", the 14" viola will be most comfortable.