A Basic Approach to Sizing String Instruments


A Basic Approach to Sizing String Instruments

Proper sizing of string instruments can at first seem mysterious. Much of this mystery comes from the different sizing terms and sizing needs used for each member of the string family. Below is a discussion of each instrument’s terminology and sizing considerations, intended as a resource for educators and parents. This is not intended to replace the knowledge of an expert in sizing string instruments, however; who should always be physically present to assist in measuring.


Violins are available in quarter increments from 4/4 down to 1/4th; as well as smaller 1/8th, 1/10th, 1/16th, and 1/32nd sizes. A large majority of teen-aged students should be able to play on a full-sized instrument. Generally speaking, students should expect to move to a larger-sized instrument every other year, with 8-year-olds often playing on 1/2 size, and 10-year-olds often playing on 3/4 size instruments. These are rough guides though; and much depends on the size of the player, and especially the length of the student’s arms and shoulders.

Because of variations in each student’s size at a given age, there are more accurate ways of sizing violins; which require the student to be present during sizing. One is to hold the violin in playing position, and have the student cup the palm around the very tip of the scroll. If the student has a natural 95-degree bend at the elbow in this position, then the violin is likely a playable size. Another sizing method is to measure the arm length from the player’s base of the neck to the cup of the palm. Generally, there is a two-inch arm length range for each fractional size: 18.5” will require a 1/4 size, 20.5” will be in the range of 1/2 size, 22.5” will require 3/4 size, and a student over 23.5” can be ready for a full-sized instrument.


Violas, unlike violins, are sized by the length of the instrument’s body. The “junior” size viola is sized between a 3/4 and a full sized violin, with a 12-13” length. This size is often used by students who would otherwise be playing on a 3/4 violin, which means that a viola may be sized larger than a violin would be for the same player. This in turn means that the teacher needs to use caution not to have the student overstrain the hand and arm while playing.

The “intermediate” viola is an additional inch or two longer in body size, and often lasts the player up until the teenage years, once their arm length is generally over 23.5.” When the student has a playing arm length of 25,” then a 15” instrument theoretically becomes usable. For each inch that the player’s arm grows, an additional 1/2” of instrument body size can generally be added in the equation, at the teacher’s discretion and of course considering the student’s comfort.


Cellos, like violins, come in fractional sizes. But where the size of the violin is often based on arm length, on the cello the student’s finger span is a primary consideration. Generally, a cellist who can comfortably extend 6” or more between the tips of the index and pinkie fingers should be able to play on a 4/4 instrument. Some adults still play on a 7/8 instrument, so not every student will play a full-sized instrument. For each inch less in playing span between the two outer fingertips, a smaller fraction should be assigned. So a 5” span generally means a 3/4 sized instrument, and a 4” span a 1/2 sized one. The arm length is also a consideration though, as students with long fingers but shorter arms may not be able to place the bow in a good sounding place on a larger instrument’s string.


Double basses are also listed in fractional sizes, but in their case the fraction refers to string length and does not refer to instrument size. Basses labeled as 4/4 are very rarely used, and should never be used by students: Most professional players play on a 3/4 sized instrument. Students in middle school generally play on a 1/2 sized instrument, whereas beginning players in 4th or 5th grade should generally play on a 1/4 size. With sizing bassists, a combination of finger span, arm length, and body size should be considered. To assess finger span, have the student make their hand into a comfortable playing position. More than a 5” span between the tips of the outer fingers will be needed to comfortably play the lowest notes on the E string of a 3/4 sized bass. The bow arm should be long enough to touch the bridge while in playing position, and physically the student should be able to span the entire range of the instrument without strain.


This chart summarizes the information presented above.

15 years-adult:

25” or greater arm length

Min. 6” finger span

13-15 years old:

23.5” to 25” arm length

5.5” finger span

9-12 years old:

22.5” to 23.5” arm length

5” finger span

7-9 years old:

20.5” to 22.5” arm length

4” finger span


18.5” to 20.5” arm length

Viola15” and aboveIntermediate 14” to 15”Junior 12” to 13”
Cello4/43/41/2 or 3/41/21/4
Bass3/41/2 or 3/41/21/41/8 or 1/10

In general, do not size a student with a larger instrument and expect that he or she will grow into it. This makes playing very difficult, and is certainly more dangerous physically. In fact, the student may not even be able to reach all notes if the instrument is too large for the player. As mentioned before, work with a capable string instrument specialist, and consider and confirm that any string rental program allows the student to move in size as part the rental agreement. Each student grows differently, and therefore the teacher needs to evaluate the needs of each student individually on a consistent basis—including instrument size, shoulder rest needs with upper strings instruments, and endpin length with lower strings. Finally, be sure to match the bow size to the instrument size, and be sure that the bow is balanced, well weighted, and matched to the instrument.

Numerous print and digital resources exist to assist with proper sizing. Any resource, including this one, is meant to be a guide, and authors of this or any guide are never responsible for problems, including injury, from following the information contained herein. With proper sizing however, the risk of discomfort and injury is lessened; and the teacher’s work can be focused on making great music, because of—not in spite of—each student’s instrumental setup.

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