Use a jacket that currently fits student and measure from armpit to armpit for measurement WIDTH and from top of shoulder to bottom hem for measurement LENGTH. Compare it to measurements below for approximate size.

XS - Width: 48cm Length: 64cm
S - Width: 53cm Length: 67cm
M - Width: 56cm Length: 67cm
L - Width: 60cm Length: 67cm
XL - Width: 65cm Length: 70cm
2XL - Width: 70cm Length: 72cm

Regatta Jackets are mens sized.