What size guitar does a child need?

The size chart

The fraction in a guitar size is a rough convention rather than a literal proportion — a 3/4 guitar is not three-quarters the length of a full one. The number that actually varies is the scale length, so it is listed here alongside.

For reference against real instruments: a Squier Mini Stratocaster is 22.75 inches and sits in the 3/4 band; a Yamaha JR1 is 540 mm, about 21.25 inches, which is at the small end of 3/4 and overlaps 1/2. Manufacturers are not consistent about the labels, which is exactly why the scale length is the number to compare.

Why height beats age

Children of the same age vary enormously in size, and what a guitar has to fit is arm length and hand span, not birthdays. A small eleven-year-old and a tall eight-year-old will frequently need the same instrument.

The chart above is a starting point for narrowing the shortlist. The check below is what actually confirms the fit.

The ten-second fit check

Sit the child down with the guitar on their right thigh in normal playing position (left thigh if they are left-handed and playing a left-handed instrument), and look for three things.

The fretting arm. They should be able to reach the first fret — the one nearest the tuners — with their elbow still hanging comfortably at their side, not stretched out and locked. If reaching the first fret straightens the arm, the scale is too long.

The strumming arm. The forearm should rest over the top edge of the body with the hand falling naturally over the sound hole or the pickups. If the child’s shoulder has to lift to get the arm over the body, the body is too deep or too wide. This is the check that catches an oversized acoustic, and it is the one people forget because everyone focuses on the neck.

The hand. Ask them to put one finger on each of the first three frets on the thinnest string. If the hand has to move to reach the third, or if the wrist bends sharply, the fret spacing is too wide.

Fail any one of the three and go a size down. There is no partial credit here — a child cannot compensate for a bad fit the way an adult can.

The body size trap

Scale length gets all the attention and body size causes as many problems.

A full-size dreadnought acoustic body is around 412 mm across and up to 118 mm deep. A 3/4 acoustic like the Yamaha JR1 is 317 mm across and 80 to 90 mm deep. That is nearly 100 mm narrower and 30 mm shallower, and it is the entire difference between a ten-year-old being able to get their arm over the instrument and not.

Electrics largely dodge this because a solid body is thin. It is specifically the acoustic where an otherwise correct scale length can still come with a box the child cannot hold, which is why we call it out separately in the acoustic roundup.

When to size up

Sooner than you would think, and this is the one place where the “too small” direction has a real cost too. A child who has visibly outgrown a 1/2 size will find the frets cramped and their fingers crowding each other on chord shapes, which is its own kind of discouraging.

Run the fit check every six months during a growth spurt. Re-run it before every new school year. And when the answer changes, sell the old one — children’s guitars in good condition move quickly, because the family behind you is about to have this exact problem.

If you are still deciding between instrument families rather than sizes, our guide to a child’s first instrument covers drums, keys and ukulele on the same physical-fit basis, and drum sizing by age does the equivalent job for kits.