Shell Size to Height & Diameter (#20)

Their size, based on a distinctive unit, categorizes the shells of aerial fireworks. The number indicates the inner diameter of the fireworks launcher. Big fireworks shells are also measured in the Japanese unit called shaku (=30.3cm).
#20 shell = 2-shaku-dama’s outer diameter is approximately 58.0cm
Fireworks with bigger shells rise higher and form a larger sphere in the air.
The height at which #20 shell (2-shaku-dama) scatters: approximately 450m
The diameter of which sphere the fireworks shell forms: approx. 450m (approximately 225m radius)
#40 Shell is the Biggest Fireworks in the World
The biggest fireworks shot off in Japan – and the biggest one in the world – is the 4-shaku-dama (#40 shell) launched at the Katakai Festival in Ojiya City, Niigata. It forms a flower-like sphere with a diameter of 750m and a height of 750m in the night sky.
The photo shows the biggest fireworks in the world with the shell’s outer diameter of 114cm and a weight of over 400kg. It disperses at an altitude of 750m and forms a 750m-diameter sphere.