Measure once, rent right. Neck to mid-palm, arm straight out, palm up.
| Arm length | Violin size | Typical ages |
|---|---|---|
| 14″ or less | 1/16 | 3–5 |
| 15.5″ or less | 1/10 | 4–5 |
| 17″ or less | 1/8 | 4–6 |
| 18.5″ or less | 1/4 | 5–7 |
| 20″ or less | 1/2 | 7–9 |
| 22″ or less | 3/4 | 9–12 |
| 23+″ or less | 4/4 full size | 11+ |
Ages are a guide; arm length decides. Viola and cello size differently — ask at fitting. Between sizes? Take the smaller. Always.
Your child will pass through 2–3 sizes before full size — which is why strings are the one family where our calculator usually says rent (good programs swap sizes free) until they reach 4/4.