Half chest can be doubled for full chest measurements and length is the length of the dress shoulder to bottom of tulle.
1-2 ~ 40cm length | 20cm half chest
3-4 ~ 25cm half chest | length 50cm
5-6 ~ 30cm half chest | 60cm length
7-8 ~ length 65cm | 32cm half chest
9-10 ~ length 70cm | 34 cm half chest