The external dimensions of a closed wooden box are 62 cm,

External length $=62 \mathrm{~cm}$

External width $=30 \mathrm{~cm}$

External height $=18 \mathrm{~cm}$

$\therefore$ External volume of the box $=62 \times 30 \times 18=33480 \mathrm{~cm}^{3}$

Thickness of the wood $=2 \mathrm{~cm}$

Now, internal length $=62-(2 \times 2)=58 \mathrm{~cm}$

Internal width $=30-(2 \times 2)=26 \mathrm{~cm}$

Internal height $=18-(2 \times 2)=14 \mathrm{~cm}$

$\therefore$ Capacity of the box $=$ internal volume of the box $=(58 \times 26 \times 14) \mathrm{cm}^{3}=21112 \mathrm{~cm}^{3}$