Cello, Viola, and Double Bass Sizing Guide for Children
A complete sizing reference for cello, viola, and double bass — with measurement methods, size charts, and practical tips for getting the right fit.
Why Sizing Matters for String Instruments
Getting the right size instrument is one of the most important things you can do for a young string player. An instrument that's too large forces awkward posture, creates tension in the hands and arms, and makes playing physically uncomfortable. An instrument that's too small restricts sound quality and limits technique. Either way, the wrong size actively hinders your child's progress and enjoyment.
If you're looking for violin sizing, we have a dedicated violin sizing guide that covers everything you need. This guide focuses on the other three orchestral strings: cello, viola, and double bass — each of which has its own sizing system and measurement method.
Cello Sizing Guide
Cellos use a fractional sizing system similar to violins, ranging from 1/8 (the smallest commonly available) to 4/4 (full size). The key measurement is your child's arm length, though height is also a useful reference.
How to Measure for a Cello
- Have your child sit on a chair with their feet flat on the floor, knees bent at approximately 90 degrees.
- Ask them to extend their left arm straight out to the side, parallel to the floor, with their palm facing forward.
- Measure from the base of the neck (where the neck meets the shoulder) to the centre of the left palm.
- Use the chart below to find the appropriate cello size.
When seated with the correctly sized cello, the top of the instrument's body should rest against your child's chest, roughly at the sternum. The C peg (the lowest tuning peg) should sit just behind and slightly above the left ear. The knees should gently grip the lower bouts of the cello without straining.
Cello Size Chart
| Cello Size | Typical Age Range | Arm Length | Approximate Height |
|---|---|---|---|
| 1/8 | 4 – 5 years | 40 – 43 cm | Under 100 cm |
| 1/4 | 5 – 7 years | 44 – 49 cm | 100 – 120 cm |
| 1/2 | 7 – 9 years | 50 – 56 cm | 120 – 135 cm |
| 3/4 | 9 – 12 years | 57 – 62 cm | 135 – 155 cm |
| 4/4 (Full Size) | 12+ years | 63 cm+ | 155 cm+ |
Tip: If your child is between sizes, go with the smaller one. A cello that's slightly small is far easier to play than one that's too large. Their teacher will let you know when it's time to size up.
Viola Sizing Guide
Viola sizing works differently from cello and violin. While violas technically come in fractional sizes for very young players, from about age eight onwards they are measured by body length in inches. This is because "full size" isn't a fixed concept for violas — adults play violas ranging from 15 inches to 17 inches depending on their arm length and hand size. The right size is whichever fits the player comfortably.
How to Measure for a Viola
The measurement method is the same as for violin:
- Have your child stand up straight with their left arm extended fully to the side, parallel to the floor.
- Turn their palm so it faces upward.
- Measure from the base of the neck to the centre of the left palm.
- Use the chart below to find the appropriate viola size.
Viola Size Chart
| Viola Size | Typical Age Range | Arm Length |
|---|---|---|
| 12 inches (Junior) | 5 – 7 years | 47 – 51 cm |
| 13 inches | 7 – 9 years | 52 – 56 cm |
| 14 inches | 9 – 12 years | 57 – 60 cm |
| 15 inches | 11 – 13 years | 58 – 62 cm |
| 15.5 inches | 13+ years | 62 – 65 cm |
| 16 inches | Older teens / adults | 65 – 67 cm |
| 16.5+ inches | Older teens / adults (longer arms) | 67 cm+ |
Note for violinists switching to viola: Many children start on violin and transition to viola later — often at their teacher's suggestion or because the school orchestra needs viola players. A child playing a full-size violin will typically start on a 14-inch or 15-inch viola, depending on their arm length. The fingering is similar but not identical (viola reads alto clef rather than treble), and the wider string spacing takes some adjustment.
The Physical Check
Once your child has a viola in hand, a quick physical check confirms the fit:
- Hold the viola in playing position under the chin.
- Extend the left arm along the instrument toward the scroll.
- The fingers should curl comfortably around the scroll with a slight bend in the elbow.
- In first position, the left hand should be relaxed, not stretched or cramped.
Double Bass Sizing Guide
The double bass is the largest of the string instruments, and sizing is particularly important because of the instrument's sheer physical size and the demands it places on the player. Children rarely start on full-size basses — most young players use 1/4 or 1/2 size instruments, and many secondary school students play 3/4 size, which is actually the standard orchestral size used by most adult players.
How to Measure for a Double Bass
Double bass sizing is primarily based on the player's height, as the instrument is played standing (or perched on a tall stool). The key reference point is the nut (where the strings cross at the top of the fingerboard) — when standing in playing position, the nut should be roughly at forehead level.
- Measure your child's height.
- Use the chart below to find the approximate bass size.
- If possible, have them stand next to the instrument to confirm the nut position is around forehead height.
Double Bass Size Chart
| Bass Size | Typical Age Range | Player Height |
|---|---|---|
| 1/8 | 5 – 7 years | 100 – 115 cm |
| 1/4 | 7 – 10 years | 115 – 135 cm |
| 1/2 | 10 – 13 years | 135 – 155 cm |
| 3/4 | 13+ years / adults | 155 cm+ |
Important note: A 3/4 double bass is the standard size for professional orchestral playing. Very few players ever need or use a 4/4 (full-size) bass — they are uncommon and primarily used for specific repertoire or by very tall players. When people refer to a "full-size" bass, they usually mean 3/4.
Practical Considerations for Double Bass
- Transport: Even a 1/4 bass is a large instrument. Consider how your child will get it to school and lessons. Many school bass players keep a bass at school and practise on a second instrument at home, or practise at school during breaks.
- Endpin adjustment: The endpin (the metal spike at the bottom) adjusts to set the instrument at the right height. Make sure your child's teacher shows them the correct endpin setting for their height.
- Standing vs sitting: Younger players sometimes sit on a tall stool while playing. As they grow, they'll typically transition to standing. Both are valid playing positions.
When to Size Up
For all three instruments, the signs that it's time to move to the next size are similar:
- The player's arm is fully extended when reaching playing position, with no comfortable bend at the elbow.
- Their hand feels cramped in the lower positions.
- Their teacher recommends sizing up — teachers are experienced at spotting when a student has outgrown their instrument, so trust their judgement.
- The sound quality seems thin or constrained for the player's ability level.
This is where renting truly shines for string players. Rather than buying and selling instruments every year or two as your child grows, you simply swap to the next size. It's seamless, cost-effective, and means your child always has the right-sized instrument in their hands.
Not Sure? Ask Us
If you're uncertain about sizing for any string instrument, the best resource is your child's teacher. They can assess the fit in person and make a definitive recommendation. You're also welcome to get in touch with us — we're always happy to help with sizing questions. And when you're ready, our instrument catalogue has cellos, violas, and double basses available across all standard sizes and tiers.
