It is best if your teacher measures you for the correct size instrument. If this is not possible, use this guide. If your child seems to be between sizes, choose the smaller size.
With the student holding the left arm parallel to the floor, palm up, measure the number of inches from the base of the neck to the wrist bone:
Arm Length (inches), Instrument Size
19 or less, 1/4 violin or 11 inch viola
19 - 20.5, 1/2 violin or 12 inch viola
20.5 - 21.25, 3/4 violin or 13 inch viola
21.25 +, 4/4 violin or 14 inch viola
Player's Height (inches), Instrument Size
57 or less, 1/2 cello
48 - 61, 3/4 cello
61 +, 4/4 cello