Singapore is about 5 times smaller than South Georgia and South Sandwich Islands.

South Georgia and South Sandwich Islands is approximately 3,903 sq km, while Singapore is approximately 719 sq km, making Singapore 18.43% the size of South Georgia and South Sandwich Islands.
Tip: This to-scale comparison of South Georgia and South Sandwich Islands vs. Singapore uses the Mercator projection, which distorts the size of regions near the poles.
Compare further: Singapore vs. South Georgia and South Sandwich Islands