You Do Need power plug adapter while traveling from Singapore to Antigua and Barbuda.

Here is Why You Need An Adapter

The outlet and plug type used in Antigua and Barbuda are A and B and in Singapore is G. This is how they look like.

Singapore

In Singapore, outlets of type G are in use.

Type G

Antigua and Barbuda

In Antigua and Barbuda, outlets of type A and B are in use.

Type A

Type B