Pattern also includes instructions to knit this as a waistcoat vest (separate Ravelry entry here).

Sizes: to fit chest
2-3 yrs (chest size 22”/56cm)
4-5 yrs (chest size 24”/61cm)
6-7 yrs (chest size 26”/66cm)
8-9 yrs (chest size 28”/71cm)
10-11 yrs (chest size 30”/76cm)
12-13 yrs (chest size 32”/81cm)

Yarn Requirements: Aran weight, 100g balls
1 (1, 2, 2, 2, 2) balls